I'll start by posting a couple of clips I've made since getting the G5n guitar processor last March (2016). First one is 100% G5n using the Hiwatt amp/cab sim. Second clip shows how I add hi-passed FX of the G5n (dirt) in the loop of the Iron Ether Divaricator pedal (B3 is actually used as the core SVT amp/cab emulation). Last clip is 100% G5n, set up to demonstrate a simulated fretless preset I made (the third take from that clip).
As a fan and user of the B3 for hundreds of gigs plus rehearsals, I got away from it due to its switching limitations, which is why I took a flyer on the G5n. Beyond the fact that the extra switches on the G5n and overall concept design suits my needs almost perfectly, I was very pleasantly surprised at how much better it sounded overall (completely subjective, so JMHO) compared to the G3/G5/B3 series. Quantifying the sonic upgrade is an evasive thing, and many may not hear much difference at all. I thought that the new algorithms just had a more realistic dynamic "feel" with increased realism. That's a pretty loose description, but that's how I feel about it. YMMV.
Clearly, the G5n is aimed at guitarists, and so I've done my share needling ZOOM about getting in the game with a new bass product featuring this platform. The B3n is what we're being offered (at least for the time being). As was the case with the G3/G5 vs G3n/G5n, there are a lot of users lamenting the B3n for almost the EXACT same reasons: no XLR; few amp models; limited number of effects; etc.
My take on this new series of Zoom pedals is that you really have to throw out what you assume a ZOOM product should be based on past pedals, and appreciate the new stuff for what it is and what it is designed to do (and do well). The lack of XLR never bothered me, although I used it a lot on the B3. I get why people are peeved about its omission. I'd rather have it than not, but it's not a dealbreaker for me. What matters most to me is the upgrade in sounds and simplicity of on-they-fly patch creating and editing. USB recording is a bonus. The patch software is pretty unimpressive, though it does its stated job. I'd really like to see this updated to be a fully functioning patch editor (not holding my breath).
Aside from the fact that the B3n is populated with bass-specific amps and features, it would be otherwise unfair for me to compare this to the G5n since I prefer the physical format of the G5n vs. the smaller B3n. For this reason, I'm probably going to hold out hope that a B5n is not far behind. If so, I'll definitely purchase one. If it's not in the cards, I'll gladly go with the B3n, if only for the amp/cab models, compression, and other finishing touches as a post stomp FX processor.
As for the limited initial offerings, I personally am not upset by this. Zoom did a respectable job updating the G5n with regular additions monthly for about 6 months or so. The G5n still doesn't have as many models and fx as previous units, but the software patch librarian indicates that there is room for another 40% of capacity for ZOOM to provide future additions, which I believe they will. I'll also say that the models that they do offer are really very good, especially for the $$$. I'm glad that I gave the G5n a chance. I think it's a worthy pedal, and based on that alone I'll say the same thing about the B3n. Since the B3/G3/G5, I think it's really hard to bet against ZOOM in the bang-for buck category. The new series is just a different direction, but certainly worthy IMHO.