As mentioned in my fork oil thread, I changed the original ones (14 year old) to a pair of regular YSS 40028. A G-Sport (gas) would have been better but these ones made huge difference. I'm not sure how the stock ones were when new but when I removed them they were very hard to push down and felt a bit sticky. They were probably the reason why my back is now sh**ty. After recovery I'll see how the new one will affect me but so far with the few rides since the change, I could feel it's so smooth that I could not recognise the same roads I usually take, I used to feel all their imperfections, now it's like riding on a cloud. Of course, the new suspensions don't remove all vibrations, medium bumps are still felt but are not jarring.
The rear YSS in combo with fork oil change definitely did change the rides for the better.