Sure.
To date I've been involved as a play tester for pretty much every one of Robert Reed's major surround releases, including all his solo work, most of the Magenta surround catalogue as well as his Cyan, Kompendium, Kiama, ChimpanA, Cursus 123430 and The Ringmaster projects.
I've had a much more "proactive" role in Bruce Soord's many projects, such as his solo material, the more recent Pineapple Thief albums, and his work for others on the Kscope label, like Anathema, Riverside, Katatonia etc. (By "proactive" I mean that I was very influential in his early days as a surround engineer: As well as play testing, I was initially helping/coaching him to develop his approach to mixing - things like using discrete placement, where best to position things in the surround field, mixing vocal harmonies in surround, being light on compression etc. )
I also played a similar role but even more "proactive" with Rob Aubrey (Big Big Train) and Max Reed (The Enid.)
I don't want to create the impression that the release I am currently involved with will necessarily be by one of these engineers/artists, but this should give an idea of the kind of thing it is going to be...
(Not related to the subject, but I should also stress that the engineers I mention above all quickly "out grew" me. I still help now and again with placement suggestions, but they make 99% of the mixing decisions these days, and hand me a virtually complete, good to go mix!)