I've mixed 2C-B with a few things! I've posted some of these elsewhere but I'll post them here again.
2C-B + LSD: I liked this, the 2C-B centered the LSD a little bit, but not as much as 2C-I and LSD did. Visuals were very colourful and nice, comfortable body high, good overall.
2C-B + 2C-I: I didn't really think that mixing these two added much to each other, but this may be partially due to my slight 2C-B tolerance at the time, but I don't think it could have been too much. I know several people who've enjoyed it however.
2C-B + 2C-E: All right, the 2C-B added some nice colour effects to the 2C-E space, but the body feelings of the two never quite knit and felt layered. It seemed almost pleasurable, but wasn't. I took the 2C-B at the same time as the 2C-E and it wore off very quickly as well, mostly done by the 6 hour point compared to the 8-10 hours I needed for the 2C-E. It wasn't a waste of a trip exactly, but I would rather take them separately.
DOM + 2C-B: Great! DOM's pretty rare, unfortunately, but these two go pretty great together. The 2C-B seems to give the DOM a very nice sort of warm glow. If you happen to have some DOM but it's not strong enough for your liking, 2C-B adds a great mood lift to it and makes the visuals much warmer and colourful as well, and I don't find that the body load is too much worse than it is on DOM alone, although of course YMMV.
2C-B + MDMA: I've attempted this twice, and have yet to get the spacing right. The first time I took a pill, waited an hour, then took the pill of 2C-B. It was nice, but nothing spectacular, but I think a large part of the was because of not enough MDMA. The second time I took the 2C-B first and then redosed a little bit more one hour after, and then took a pill (different, weighed out at ~130 mg) a half hour after that, but then for some reason the two highs never stabilised into each other. I felt like I was missing the loved up and soft feelings of the MDMA as well as much of the interesting headspace of the 2C-B. I had heard that they antagonised, and now I think that's what happened to me. I snorted a little bit more 2C-B (~6 mg maybe) later once I was coming down from the MDMA and it was very nice, though. I think it's just a matter of spacing with these two drugs, but I have high hopes for them. Next time I'd like to try taking the MDMA first and waiting until it finishes, and then taking the 2C-B, like Shulgin, and apparently most people here suggest.