It rides like a rigid bike with 20lb wheels in the summer, meaning you’ll get bounced to hell when you pick up any speed or try to roll something downhill. The reasons a fatbike works in the winter is that you are limited by traction as far as speed, you run much lower psi, and the snow absorbs a lot of impact energy, even when it’s fairly “hardpack”. I would want suspension riding one in the summer and even then, it’s way more of a chore and limiting to me, but in the winter I’m never feeling like I want suspension.
If you are at all riding in icy/hardpack conditions, studs are money well spent. It feels like Velcro on hardpack and makes ice at least possible. The skinny 4” and less actual stuff ruts our the trails like crazy. The D5 is an amazing all around tire that rolls well. It only comes out to about 4.4 on 90mm rims. I couldn’t stand the d4, there are a lot up here but I think it’s a left over from when that was all we had. It’s just too skinny to be fun in actual winter conditions and doesn’t roll noticeably better. Rocking J5s on the big fat bike for the winter, but haven’t switched over yet because winter hasn’t hit Alaska. Was 60 degrees last week.