I've used both 9' and 10' 7wt.and 8wt. GlX's, XP's and an assortment of others. In terms of length, I prefer the 10 footers but an additional 6" might be nice. The additional length helps with the mending and gets more line off the water when wading deep.
I like the overall stiffness (especially in the tip) of the XP because it seems to manage the terminal end (long leader 14.5', indicator, shot and tandem flies) with less effort. I have just purchased the Crosscurrent GLX 9' 7wt. and am very impressed. It would be fantastic to see this action in a 10 or 10.5 footer.
For me long belly lines are the only way to go. I've used SA's
steelhead, nymph and xxd lines and like them all.
When I get to swing flies, which is infrequent, I still prefer the stiffer rods.
In terms of reels, I love the Harris Solitudes. Cheers.