Agree with the analysis so far. There is little FFing at the GAOS. There is a good amount of general fishing booths, but I agree the majority of them are guides showcasing their lodge's/trips. There's some good deals to be had there on that sort of thing, if you're into it.
In short, I wouldn't go to the GAOS just for the FFing. If you're into hunting and other outdoor sports too and want to check out the whole show, then it's worth admission IMO. Or, if you're looking to book a guided trip and want to meet with some outfits, it's a good place to do that. It's VERY busy on the weekend days. I don't go every year, but every few years I enjoy spending a day there. (Convenient timing at the coldest part of the year when there's nothing better to do most days.)
If you're looking for just FFing, you'll probably enjoy The Fly Fishing Show in Lancaster (March 7th/8th) more. Much smaller in scale, but all FFing.