I used to do sound design at WGS and build the WGS speakers. Here's my take.. Vet30 is a great speaker in some amps, Mesa being the most IMHO. Side by side the V30 and Vet30 here's my findings: the Vet30 is more bass heavy, less mids, and thinner high end- the V30 from Celestion has tighter bass and less of it, punchier more 3D mids that cut better in a band mix, and more pristine crystal clear highs. I've AB'd these speakers extensively and they are both great speakers. It all depends on the amp your playing of course and I think most Bogners, especially the Shiva sounds best with a Celestion V30.
The Shiva to me is already a pretty warm bass heavy amp, and the WGS VET30s only take away some of the magic of the Shiva. Now a Reaper 50 I have yet to try but I bet it would sound great. The Green Beret would sound good too I imagine.