I am running 9c without too many issues. I do get moments where it stops responding for 5-10 seconds at a time as noted in the forum.
I have gone through the 9d posts, noting that some people are experiencing slow .veg loads, others aren't. I don't use the program commercially and could roll back to 9c if needed, so this isn't a critical situation.
I am curious though if most people are happy with 9d over 9c. Of course, people with issues are the ones that tend to post, but it seems to me there's probably a lot of happy silent users of 9d and interested whether they would chime in with a simple 'it's OK for me' kind of post to help those of us on the fence.