Sharing my first impression of my 8k+ which arrived today.
First I will start by saying that there is definitely more attention to the small details from Pimax in regards to packaging and the quality of the unit itself. Packaging, and the general feel of things are an upgrade from both the original 8k and 5k plus.
I will start by stating that I don’t use my headset for anything other than iracing. It’s the only sim and experience I’m interested in so this will be to a limited audience. First I will say that all noticeable SDE is gone, which wasn’t a huge problem for me with the 5k plus anyway. But there is certainly an improvement here. I haven’t messed about with settings a ton to this point, however I can say that there is a difference here with how steam and pitool function together, which to this point seems to provide a bit more head room and an overall smoother experience. As many have pointed out on this forum the newest versions of pitool are not ver cooperative with iracing and the judders are still an issue with the 8k+ as well, so it’s definitely a software issue for the 5k+ users fighting those same problems 
Alpha 254 does eliminate the stutters for me but had random crashes with extended use, so I’m currently using version .132 which seems to be most favorable for me.
In regards to the question of being worth the upgrade for iracing in particular, I have to say it’s not a huge step up to this point from my 5k+. I think it speaks for the quality of IRacing’s VR experience, and how well the sim already performs in VR. There is less SDE for sure, and it does seem to run smoother overall, but the last little bit I’m looking for with this sim is clearing up the jaggies and blur in the distance, which doesn’t seem to be any better with the 8k+.
The comfort kit is a very nice addition and feels much better than the 8k and 5k+. Not sure if it’s the spacing, but my IPD setting in much smaller than what I used for the 5k+. I settled at this point on 62, where I was at 66 with my 5k. I will play with things a bit over the next week and add some additional thoughts later on.