norman,
i recently upgraded from an N90s to an F5 and i am loving it!! if i
were going to upgrade i would either get rid of the N90s or the F4 and
get an F5. i would base which one to keep on which one i liked better.
i prefer the N90s for it's electronic interface (easier to switch back
and forth from an F5 to an N90s than to an F4 IMHO) but the F4 is a
wonderful camera too; built like a damn tank. it's all about which one
you want in your bag with that other lens on it.
i would go for the F5 over the F100. you have grips on everything
now, so i assume you would get the F100 grip (whenever it comes out.)
the F100 is costing about $1300 (please correct me if i'm wrong) and the
grip would probably be another 150-200...so you're looking at about
$1500. i would rather have the grip built into the camera and pay
another $400 for the option of having 8 frames per second. the grip
being built in and the faster motor drive along with the slight price
difference (once you get above a grand what's $400 more? ;) is what
confirmed my decision to go with the F5 rather than the F100.
i'm sure some people are going to say that being able to take the
grip off is a bonus for the F100 but i shot with my N90s for 2 years and
never even considered taking the grip off. also, like some other
listers, i like the weight of the F5, it doesn't slip off my shoulder as
easily as my N90s and it balances better with heavy glass. as i haven't
had a chance to play with an F100 (stupid local camera stores....) i
don't know how it feels. how it feels in my hands is a very big factor
with how i like the camera. the N90s with the mb10 feels good but the
F5 feels better.
of course that's just my opinion,
eric