Well, yes, there are several different altissimo fingerings for F# - it'll depend on your particular instrument which will respond the best and be most in tune. You need to practice all the alternate fingerings for any note that has alternate fingerings as you never know when you'll have a passage that needs one or another of them. The all-palm-keys high F#, for example, will be very awkward to get from, to notes that close the upper stack - so for example to go from the all-palm keys high F# to G, will be a real bear to get it timed right. What to do, what to do? Well, because I also regularly practice a high F# fingering of 1 3 4 (LH index and ring, RH index), I've got a fingering that is an easy transition from high F# to top of staff G.