I've been giving some serious thought about getting this lens lately, so if I do I'll definitely let you know!
That said, the reason I haven't gotten it yet is that I usually just use an adapted vintage 50mm lens and they work great. My go to is my Yashica ML 50/1.4, but I've used a bunch of different ones.
I find peaking works very well, though a bit hard to nail focus sometimes on my X-E2 (was the same with my X-E1) without zooming in on the focus point.
I actually prefer the way the focus assist works on the XP2 with the OVF and ERF for focus peaking, it's sped up my MF process a good bit and increased my hit rate (something I didn't expect going into the XP2).
I have several Samyang lenses though and all of them are fantastic, among my favorites in fact. I have the 12mm f2, 21mm f1.4 and 85mm f1.4... I've also owned the 8mm f3.5 (EF mount) in the past.
You also may want to wait for the rumored XF 50mm f2 lens that's supposed to be coming out in the next few months. It should have the same (very good) focus system of the 35/2 and 23/2 in a similar body to those lenses as well.