Sounds pretty much like the typical 15 vs 210 sound profiles, and 350w vs 140w. Granted to really push them in. GC is hard to get away with. 210 s are scoopy so the OD will sound more natural on a 15 unless you eq to compensate, and 210 always has that punchy articulation, but the 15 in the rumble is almost like the 15 in the son of bertha which had a very fast reponse for a 15. The SOB and the R200 have been the only 115 that I have really enjoyed on its own. Though I can only remember one time I decided to gig with just the SOB, and my mids were angrier than ever that night. Usually I used the goliath III and only brought the SOB to make the full stack. Had the SOB not been stolen I would be using that with the 200c. I would argue that the 15 will cut through a band mix better because it is that hair on the mids that does it. 10s tend to be more transparent, solid lows and clearer highs but scooped mids. Of course you can eq to compensate either way and are not stuck solely by the speaker profiles. Old school thinking was put the 15 on the bottom. We thought the 15 was like a sub and the 10s were like mids when in reality it is the opposite. I can only imagine how much better definition and dispersion I would have had had my 410 been on the bottom and my 115 on top. It would have made me look like a "noob" back in the 90s, but man I wish I did that . now with the 200c the 210 acts as a sub and raises that 15 higher which is a huge benefit. And the grilles cover up the optical oddities. I had used the 200c with an ampeg 210 from the black mini svt, at my first gig with the 2000 in 2015, and used my working man 10 cab with it in a few rehearsals. The SOB got stolen later that year along with the wm110t and wm10 amp, my goliath Jr II and bass350 amp/rack as well as a guitar cabinet and other small valuables including a gold watch when I ran out of gas in Victimville later that year. So my rumble has been played through acoustic b115 in a rehearsal studio, an acoustic b115neo that was backline at a show, 2x because I liked it so much the first time that I did it again. So really any decent 115 makes a slamming addition to it. Of course the 112 was what I used for most of the other gigs but if I had a chance to plug into a bigger cab I would. One time there was a 212 GK cab, and that thing absolutely slammed, reminded me of the days playing the big SWR rig. I have yet to really crank the 210 yet, but it sounded good the 2 rehearsals I used it at before deciding to leave it at home. I am pretty sure it will slam pretty well though, but 212 is much more air than 115, and that made a difference that one time. If you end up with a 500 you can always add a 115 and if you get a 200 you can add a 210 and in both cases get the best of both worlds despite what the mixed driver police says. But in their defense, those backline gigs where I put the 200c on top of the 115neo bottom cab from the backline rig, which is very similar in dimensions to the rumble combo, something magical did happen. All those years as a 10s guy... And I find I really like 15 s. Or having both because f the MD police!