As luck would have it, I went to a brew day yesterday with two other home-brewers (I've brewed with these guys a few times over the last 12-18 months). We did 3 beers concurrently (a RIS, Hefe & a Saison). One of the guys (not on this forum) brings his 20 litre BM, so as you can imagine I was all over his system like a rash.
What I found really interesting though is that he doesn't use any of the BM's programmable mash temp features, basically just puts the BM in manual mode, heats his water to strike temp, then puts in the malt pipe and pours the grain. He tells me he always does it this way, i.e. a single infusion mash.
He also doesn't bother sparging at all, just pulls the malt pipe at the end of the mash, and lets it drain back into the BM. He gets around 65% efficiency, and simply adjusts his grain bill to work with that. Once the grain is out he manually sets it to boil temp, and when it beeps to say it's there, hop additions start.
Now what struck me the most about all of this is his process doesn't really seem to do much that BIAB doesn't already do? I know this is just the way he does it, but I just found it interesting. If you don't need/want a step mash, what is it the BM is doing to make brew day so much simpler/better than a BIAB process? I was surprised his efficiency was the same as mine (I currently BIAB), given the BM pumps all that water around during the mash, I would have thought that'd increase efficiency significantly.
I'm still very keen on a BM, don't get me wrong. But it was a bit of an eye opener, I have to admit. Oh, and of course this thread is about 3V vs BM, so apologies that it's off topic. I'll go looking for some BM v BIAB threads to see what I'm missing.