tIANci - for most things we do in this hobby, we needn't (shouldn't) ask why. there is no logic in this hobby... we do it for the sheer joy or rush of it. you must like the harrier. personally, i think the F40 and F90 are a little generic. something like the harrier, though not as "pretty", has a lot more pizzaz. that's why i added so much additional graphics on my F40.
update on my addiction. i've finally stopped my purchases recently. though that has something to do with the fact that i didn't win two engine bids on ebay :-) but i haven't bought a plane in a month. i'm not staying up till 2-3am in the morning assembling new planes. the plane i'm currently building, the second WM Cub .26 w O.S. 30FS, is coming along nice and slow. it's been two weeks and i've yet to CA the control surfaces on. but i'm going to see if I can have the plane up this weekend.
by the way, it's been way too long since we last hijacked a thread!
so to bring it back - warning, if the F90 is the plane you want, why not? as someone said, get it on buddy box and you should be fine as long as you can do what i suggested, fly inverted around the pattern a couple of loops. and while your at it, pick up some extra tri stock to reinforce the gear area. and whatever you do, DON'T fly at high speeds. i'd recommend you start with an APC 13 x 6 prop since they are much cheaper than the 14's and don't over power it. fly around at no more than half throttle unless you are going directly up.
honestly, though, i think you'd have a lot more fun with a low wing trainer. doesn't this look nice?