1" threadless works exactly the same as 1 1/8" threadless, so to convert from a threaded system you'd have to buy and install a whole new headset (and stem/spacers), but if you're willing to do that it's not a bad setup at all. Only other catch is nobody makes 1" threadless stems, so you have to use a shim with a 1 1/8" stem, but a lot of stems come with a shim for that purpose, so again, not really a big deal.
I've looked at that SOMA fork, it looks nice and comes with a nice long steerer tube (350mm) for getting the bars up high. If i ever get around to replacing the uber-flexy cross check fork on my Trek 520 (which came stock with 1" threadless, kind of interesting), that's probably what I'll go for.