I see great potential in this style, I have always been a strong beliver in that a fixed system will have an advantage of a free one when it comes to thinking speed once you get used to it. ST stacking has been that for me, im almost as fast with ST stacking as with normal stacking (tetrises) since I know where the peices should go. Though this way is way better than ST in 40L (obviously) as it more effective in keypresses per peice.
Good work. I once tried exactly the same tactic in KeyBlox, But I couldn't get as fast as you (even with 1-key finesse).
Damn, that was pro! Like the way you stack ^^,