Oh, man, I shouldn't even get started here, LoL. :-)
Yeah, for me, there is nothing that compares to the feel of an alpine setup - having everything balanced on that one edge, and just slicing along on that edge all the way through the turn, is truly intoxicating. You can literally see a thin, snaking line the whole way down the hill, with no breaks other than the brief moment where you transitioned from edge to edge (and even then, one snaky like ends as the other starts right beside it). Depending on the board, some are more inclined to just make large, sweeping turns, but some (like the MK and slalom boards) can make shockingly-tight turns, too (the MK is pretty good at both large-radius and smaller-radius turns) - the catch being, everything is happening at warp speed, regardless of the turn radius. People always comment how fast the board is, and I always reply that I spend about 80% of my energy just trying to slow it down. :-) (Through constantly carving turns, and trying to make them fairly tight - but the thing is, when you're riding on edge the whole time, there's not much friction or drag to slow things down!)
The edge-to-edge speed of the narrower boards is astounding - it can almost take on a life of it's own, with your upper body staying pretty much in place, and the board and your lower body just zipping back and forth underneath you like it's got a mind of its own - if you're making small, shallow cuts when on flatter/smoother terrain, transitions between pitches, etc. (And for me at least, it's kind of a necessity - I pretty much constantly have the board on one edge or the other - riding flat on an alpine setup is a recipe for a nasty edge catch, as there is typically little-to-no bevel on the board or the edges, and any body movement translates pretty immediately into edge input, whether you intended it to or not.)
Like any boot, finding a boot that fits you well, and getting it dialed in for your foot is critical. I've had hardboots that fit really well, and others that have not fit particularly well. In a good fit, you'll get about zero heel lift, but you don't want that at the price of having to crank things down so tight that you lose circulation in your feet and are constantly thinking about getting out of your boots. I'm presently on a pair of UPZ boots, with heat-moulded Intuition liners, and some minor fit customization (customized foot beds, some minor additions to the outside of the liner to help hold my narrow feet well in place), and they're definitely the most performant boots I've ever had. TBH, I'm quite happy to get out of them at the end of the day, but I've finally gotten them dialed in to the point that they're not painful. (Even early on when they were painful, I still wore them all day because they simply kick ass on the board! :-) The most comfortable boots I ever had were an old pair of Burton Shadows, but alas, those are long gone - though not really 'alas', as while they were the most comfortable, they were definitely not the most high performance, and would not have worked well on a demanding beast like the MK...
That video you linked makes some very good observations. I think Ryan under-rates some aspects, as he's so used to a softboot setup, but he largely hits things on the head, IMHO. (Switch riding sucks - every time I've tried to carve switch, I've broken something on my body, LoL. Side-slipping is truly exhausting, especially side-slipping on heel edge. The boots are too stiff and too responsive for jumps - at least for me - it's not so much the jump as the landing! I have to disagree with him on heel vs toe side carves, though - both are awesome, but toe for me is the deepest and most committed edge.)
It's hard to say, "You should try it", as there is really nowhere to 'try' alpine gear - nobody rents alpine stuff, at least not that I've ever found. If you were out in CO, and got in touch w/ Sean at Donek, he'd almost certainly let you demo something, but you'd still need your own boots. I think that's part of why it's such a niche sport - it's just not easy to get into it - you have to be financially/materially committed (and it's a big commitment by the time you buy boots, bindings, and board) before you ever try it. Getting used gear can definitely help reduce the startup cost to some degree. It sounds like it'd be a good fit for you, though, just based on what you've thus far described. Definitely lurk around
forums.alpinesnowboarder.com if you're interested, and feel free to jump in and start a thread - you'll get lots of impassioned replies, I guarantee! :-)