So I went a little wild with the WGS speaker sale last fall/winter. One of the speakers I got was a G10A. I built a Mojotone Princeton Reverb this spring and the G10A sounds great with this amp.
But, just for kicks, I decided to try a bunch of other speakers with the Princeton. I liked the 10" Veteran almost as well as the G10A. Different tone but very nice. I tried a G12Q in a 1 x 12 Extension cab (alone not in combo with the G10A). Not so good. Reaper 55hz, again, not so good. Black & Blue was great but probably a little too underpowered for the the amp.
Finally, I tried a G12C/S. It sounds really good alone. But, there was some magic that happened when I tried it in combo with the G10A. I think the extension cab is destined to accompany the Princeton forever!
Cool beans! And, serious thanks for taking the time to report your findings here where we can all learn something :-)