Aftermarket seat opinions....

have you considered trying the "butt buddy" for your +1?
Mine can't stand how small the seat feels compared to the Multi, so I'm considering trying that route when I get back in the states.

I prefer the DP racing seat over the OEM, but my OEM (2013) is pretty tired and the foam has lost some give. I always argued the OEM was a very good stock seat, however. I rode my daughter around for a couple hours this weekend. While she's only 13 and doesn't mind the tiny pillion area, it's just not a great passenger bike. The bikes geometry still puts passenger weight on the pilot and I felt it in my wrists and crotch. Constantly clanking helmets wasn't fun. Granted, she's not comfy enough to release the bear hug grip and I dislike passengers in general. If I was going to have a passenger with me often, I'd get a dedicated touring bike. Even the smoothest throttle hand on the Gen 1's can't dampen the passenger accordion effect in the 1st 3 gears.

Agreed the hyper isn't a great 2up bike. I take my S/O around the city from time to time and while I think I have pretty good throttle control the bike lurches a lot. I suspect a lot of that could be solved with suspension setup for our combined weight as I run it nice and soft for myself so I can dive into roughly paved corners with abandon. I actually found the stock seat to be more comfortable on the base hyper than the seat the SP gets for longer rides to be honest. I don't think the race seat would work well for 2up just looking at it the passenger seat seems like an afterthought. I'd see if Corbin or Sargent could doa purpose built custom seat to better accommodate a passenger.