I'm using GHS Boomers Light (.010, .013, .017, .026w, .036w, .046w) on both my '07 NiteFly and '97 Fly.
I had the same impression of the Fly - need a tad bit more tension to give you the feel of a .009 set of strings on a normal guitar - and that is exactly right IMO. I also got a lot better action and the tone is awesome on the Fly as a result too - no thinness in that sound at all. Seems like a set of 10's on a Fly will give you the feel of 9's on a Strat. The 10's on my Fly just seem to play better than 9's.
The NiteFly is a little different - 10's on a NiteFly are much easier to work and give you a little fatter tone on a NF vs. a Strat/LP, but on a NiteFly the 9's or 10's seemed quite natural to me. I stuck with the 10's for now though: I play a lot of scales and stuff, which would be a little easier with 9's, but I still like the tone of the 10's and with single coil pickups string pull and intonation is more managable with 10's.