I started with Cabrinha kites while learning but prefer North now. I weight 75klg and have two kites Rebel 11m and 9m. Their wind range is awesome and the bar pressure is so light to Cabrinha that your will love the switch. See if you can demo some North kites before you make up your mind.
Keep the two kite quiver as your only starting to jump and before long you will be wanting 35kts with your smallest kite. 2meters between kites is pretty close though, try 12, 9 maybe for the east coast.
As for Switchblades they are grunty but pull like a truck, I just bought a North fuse and a mate converted from switchies to fuses, bottom end is about the same without the heavy bar pressure. Definately worth a look at the fuse or rebel.
The colours have changed, that's about it. Every year the kites are faster, more wind range, more de-power, bigger boosting, better un-hooked, stronger, and now they can even make you a cup of tea apparently......
Keep your 12m if It's still in good condition and get yourself a 9m. This will give you a huge wind range of more than 25 knots when you decide to hit it.
Yeah keep the 12M and trade your 10M in for a 9M or even an 8M maybe. I'm 85kg and run an 11M and a 7M and find I hardly ever get to use the 7M and when I do am usually underpowered. 8M would have been just right for me.
I'm the same as ozoned. Have a 11m and a 7m. Gets me out there in all conditions, with the 11m being the most used. Keep the 12m and get an 8m or 9m would be the go.