Well, for me personally I'd pick at least one cab full of each! LOL. Here is the thing, I have 2 Avatar Contemporary 2X12 closed back cabs loaded with the BM75s and two more cabs exactly the same loaded with M75-PVC. I also have a Splawn 4X12 loaded with M75-PVC, and a Marshall 1960BX 4X12 loaded with BM75s. I have never mixed the BM75 and the M75-PVC in the same cab, but I strongly suspect they would sound great together because I have mixed my cabs together doing stereo and W/D/W and they compliment each other great. Those two speakers aren't a great deal different. The BM75s have a little less bass and it is tighter and more percussive. The BM75s also have just a little sharper upper mids and highs. Not V30 type of upper mid spike, just a little more sharp and pronounced. With my BE-100 I prefer the BM75s. They are freaking perfect for the BE-100 I think. For the SLO I tend to prefer the M75-PVCs. They are a little smoother in the upper mids and highs and have a little more bottom end. Still tight bottom end for rock and old school metal. The video of mine you watched bugs me because the low end on the M75PVCs is tighter than that video makes it sound. That camera mic distorts low end way too easy and I can't get it to not do it so far.
The only video I have of the BM75s is with my Landry G3 doing W/D/W. It is crap playing and another crappy mic (this was my phone mic) but all 3 cabs are BM75s. This is also a different amp, so take that all into account. The Landry G3 sounds awesome with every speaker I hook it up to. I don't know why, but that amp likes all speakers for some reason.
https://www.youtube.com/watch?v=NTE4ksOBYSU