Tommy
I haven't flown the Excelleron 50. I sold it to a flying buddy. I've seen him & his son fly it 3 times.
He set it up with a Saito 72 and performance was good.
It flew straight witih only a few clicks of trim and lands easy as the 90 size.
His AUW is 5pounds & 14 ounces.

I intended to set it up with the Irvine 53 and may still do that. I just picked up another one while Hobby People had them on sale for $179. I beleiver it will fly good enough to pull out as a backup at a contest.

RE your note about 4 blade props for the 91, Nat's been running them for quite a while. I'll get the size info for you. I do know some of them he re-pitched, but I don't remember the size or pitch of his 4bladers.
Eddie