I'm on the same custom (PASSION RED) and have National Cycle's 2-up switchblade shield. It's quite large on the custom, so isn't all that aesthetically pleasing, but I've gotten used to the look. It *RARELY* comes off except for the occasional jaunt when I know I'm staying at speeds under 45 and in town, or on those days when I just want that sleeker look. 5 seconds attach/detach. If I sit up straight, I can see over it easy, or I can settle in and look through it in need (i.e. rain, sand, etc.) I still get some buffeting, wind bouncin' up off my knees, but it's hard to imagine putting lowers on somehow and still keeping the quick detach function.
(EDIT: by "some buffeting" I mean wind that comes up from below the shield, and when in my full face helmet (rare), it flows right up into it... It's actually a much EASIER ride though, what with the wind off my chest, and when I go lidless, is very pleasant.)
Ol' Redemption, she still gets lots o' positive comments, shield or no, and I've settled in with the look now so it's not as drastic as it once seemed. Summer highway riding, all those fat and juicy bug-type things... well... 'nuff said. One splotch on the shield that was about half as big as my fist convinced me of the usefulness, and watching a rock about the size of a quarter bounce off of it on the super slab sealed the deal. That and a scare on one of the back road country trips with a couple of wild turkeys... (the living kind, non-liquid) Well, I'll take the shield any day!
Will see if I can't dig out a couple of pics with the shield on, but I think there's a thread out there somewhere in the 900 forums, too.