All of the above are really good tips (apart from the poo stance...).I've spent the last few months really trying to get as consistently high as I can on my Sonics, so I've got a few tips that might help. Most of this stuff is muscle memory though, so I might have it a bit wrong. I also know you are pretty experienced, so I know you probably know most of this, but I'll just put it down anyway so others can add to/correct it. I might be completely wrong on some points too - this is just where I'm at at the moment, and I feel I've been doing ok... Also, things might be slightly different with the Sonics, I've not flown any of the other newer Foil kites.
Setup and takeoff
Like others said above, the foils need a much more vertical takeoff, and a less aggressive throw/pop off the water than you would do with an inflatable. Really focus on making sure the kite is a lot higher (more vertical) in the window than you would when leaving the water with an inflatable.
"...end up with my momentum going down wind..." - this could be partly because the launch wasn't vertical enough. On really big jumps, I come back down to water with negligible downwind momentum, but if I was on an inflatable coming from the same height I would be going downwind at a rate of knots, and would most likely be looking to a downloop to catch me.
Another thing that can lead to you going downwind a lot as you are coming down is related to what Kamikuza said about the backstalling of the kite. I always have the foils trimmed so that the kite won't backstall when the bar is fully sheeted in. If it backstalls when it is pulling you upwards, it won't give you the vertical lift you want and it will start taking you downwind (which also reduces the air flowing over the kite, and gives you less lift).
If riding to the left, I would not send the kite back past 1 o'clock on the initial jump redirect - even that is possibly too much. Any more than that you really notice the kite not giving you the lift you would expect. The foils really don't seem to benefit from the pendulum effect that can benefit some of the LEI kites.
When you redirect the kite (still for the launch), sheet out to let the kite breath throughout the turn (not necessarily right out, this will be something that you just need to get a feel for on your kite), and don't throw it as aggressively as you would an inflatable. The aim is to keep the kite flying and building power, where the sudden harsh redirect you generally use with an inflatable will make the foil 'flap' a bit and not stay as efficient. If as you are going up you see the kite flap/go out of shape a little, you will be losing height/lift and will end up more downwind. When you leave the water, sheet in, but again, not super aggressively so the kite can react to the new direction/attitude without getting pulled out of shape. If the kite is trimmed so it won't backstall, you do sheet in all the way, but just more controlled/gradually than you generally do on an inflatable.
When you are leaving the water, you want to 'pop' a bit more than when jumping an inflatable. Generally, when jumping the inflatables you are trying to hold the power right up to the point where the kite is ready to rip you off the water, and then let it slingshot you into the air (and usually with a big downwind component). If you do the same with the foils, they are more likely to do the jump/flap thing, lose efficiency, and also take off with more of a downwind component than you need to. For foils, the approach/jump is similar, you just need to ensure that you keep the kite flying smoothly at all times, avoiding any sharp changes that will let the kite lose its shape.
In the air
I find you can keep the foils dead overhead for a lot longer than you can with an inflatable. They will also go a lot more behind you than the inflatables will, which is what lets you come down with a lot less downwind component. On the way up, just keep sheeted in with the kite vertical (unless the kite looks like it is starting to backstall - it will either stop moving forward or will move backward), in which case you will need to let the bar out a little to let it breath a bit.
For really big jumps, on the way down, I sheet out and angle the kite down a little bit toward the direction I will be redirecting the kite in. This will allow the kite to actually be flying powered when it comes to the redirect. I do this as a very slow arc, just enough so that I can feel the power staying in the kite. On really big jumps (11m+), you may need to actively fly the kite a little on the way down to make sure it's in a good position for the redirect. If the kite does feel like it's going too far forward, sheet in a little to try and keep it powered and ready to go.
Landing
Because you should be coming down reasonably slowly, the final redirect doesn't need to be until 1m or so off the water. With your 12, you should be able to just crank it and it will almost stop you. If it was a high jump, the kite will likely be close to the edge of the window, so you will need to really crank a 12 to get it moving back into the window, but if you have managed to keep the kite powered and high, it will still be supporting you even if it looks like it is heading at the water.
You should also not really have much downwind momentum. Unless I am at the high end of the kites wind range (on an 11m), I typically need to redirect hard to get me up to planing speed again. If you are in the in a comfortable wind range on the 12m (i.e. you are not feeling overpowered) you should also be able to downloop the 12m no worries - it will stop you dead vertically. If you are feeling really powered though, the downloops do produce a lot of speed and power...
If you haven't managed to keep enough power in the kite, or it has crept too far forward, or you don't redirect hard enough, then that is when you will risk the lines slacking and the kite is likely to fold up/wing tuck/etc, which is a real PITA.
Bottom line
Everything with the foils seems to be keeping everything smooth to ensure they keep their shape and maintain their max efficiency.
I love the way the foils jump. I still have inflatables as well, but I just can not get the height and hangtime I can on the foils in the conditions we have in Brisbane. It's not until the wind is heading into the 25+ range (which we don't often get) that the LEIs start taking over. In that range I'll be putting the foils away anyway.
I know the Woo heights can be a bit contentious, but I think they are still a good tool that can give you a long term trend on how you are doing, and on how changes you make impact your results. Individual results may not be 100% reliable, but as long as they are consistent, you can gauge how changes you are making impact your jumps over time. They do become addictive though, and sessions I would normally just go out and have fun, I will instead put up a bigger kite and see how high I can go instead...