Actually if he's looking for something like the Yelli, but that will just take the edge off, I'd have to say
Phantom over the
Prime, he'll get much closer to that nimble feel of the Yelli. If you don't know about it, 105mm of rear travel, KS Link
(multi/mini link design), adjustable geo 67.5*/68*/68.5* HTA, designed around a 531mm/120mm travel fork.
My story, coming off the same steep angled bikes you referenced - first got a Paradox, couldn't believe how much fun it was, how great it climbed, how sweet it was descending, overall the confidence the slacker geo gave. Then I got a Prime, it was heavier and burlier than the Paradox by far, it had longer stays, but the handling still felt pretty close and it out-climbed the Paradox on anything not flat , something I never thought it would, then point it DH and Whoa Moma does it ever just haul and inspire. Just now got a Phantom and had sold my V1 Paradox and got a replacement for that in a V2 Paradox, built up the Phantom with parts from the Prime, did a few test rides, loved it, perfect for me, built up the Paradox, took it for one test ride and determined that I no longer needed a HT with the Phantom. I think it would perfectly suit what you're looking for.
Yeti SB95, Banshee Prime.
