12 or 2x10 with Berg 15

I own both the 2x10 and the 1x15 and I run them w/ a Mesa M-Pulse 600 and they sound awesome together.

 

I would think the HT210 would sound better with the HT115, plus the power handling is better that way than with the 112...but, you really should listen to both combinations to tell which you like better.

I know a lot of people use the HT112/EX112 combination and rave about it, but I've never heard of anyone using the 115/112 combination. It should add punch and midrange to the sound of the 115, but the 210 would also.

 

Ive tried the berg 112/115 combo. First if you set the 115 on its side the 112 fits nice on top. For me I had to use a pre/power set up so you could turn down the power to the 115 so it wouldnt drown out the 112. Other than that it sounded good. To be honest, two 112s or the 210 would get the most potential out of the 115.

 

Although my favorite single cab these days is the Bergantino HT322, I use the HT115 and HT210 together mostly for outdoor festival shows. A killer combination, IMO. I also own an HT112 but typically use that by itself for small, lower volume jazz gigs.

In answer to your question, I believe the 210 is a much better match with the 15 than the 12. More punch and better balance. Bergantino HT's are my favorite cabs. That could change, of course, but their smooth top-end and overall clarity are the best I've found so far. I also like (and own) Epifani cabs, specifically, the T212 and T310. Very good as well but quite different and perhaps less "modern" sounding...whatever that means!