Hi, I know you're waiting for Kevin's reply but meanwhile I can try to give you some tips (just to let your post up ok? :-) )
If I were you I'd chose the Futura 155. It's a great board, very fast and I think it'll satisfy all your needs..
I think both iS and Futura would anyway give you the chance to uphaull.
Futura will give you the chance of some more jumping, and has a less technical ride to improve in jibing and a longer nose for better tacks.. (it helps..).
In stronger winds.. I dunno, with boards of this size (wide 85 for Futura and 93 for iS) it depends on rider skill and water conditions.. Maybe Futura is a bit more confortable for being narrower and less technical..
For reaching upwind, both are quite good, it depends on fin you're putting on..
Hope this helps! Bye!