Hi Michael, indeed I am using a trackpad. Zooming via two-finger scrolling on the trackpad results in large jumps, almost as though MoI is simulating a scroll wheel with notches. I have used the modifier keys you describe, though clicking and dragging is awkward to use constantly. It's unfortunate that multitouch won't happen; it's the difference between delightful interaction and tiresome frustration, and that's really a deal-breaker for me.

William