A solid case definitely changes the feel of the board. Makes it more solid, as you'd expect, similar to adding a plate. Less flex = slightly harder feeling on bottom out, more isolation of the switches. All the components have at least some effect, some smaller, others larger, but the combined effect of using all quality parts adds up to a great typing experience

The case that Pexon sells is a Vortex case and it looks to be the one they will use on the upcoming Poker 3, at least they used that case in the pre-production FB photos.
I think it's also important to point out that the V60 will not fit some Poker compatible cases, due to the larger DIP switch area. I guess most cases could be modded (by enlarging the DIP switch hole) to make it fit, though. At least they added the Poker II PCB mounting holes, the prototype didn't even have those.