I've never tried 6-mapb so I can't provide any info on that, and since you've already taken 6-apb I won't all out describe that one as much as I will draw comparison between it and 6-apdb. Personally I liked 6-apdb more than 6-apb, but I could see how someone wouldn't. 6-apdb was more outright euphoric, quite a bit more psychedelic, and the duration was similar if not longer lasting however there was very little empathy, even less so than 6-apb and side-effects are more pronounced.
I can't remember the BP readings for 6-apdb but iirc they were slightly higher than 6-apb, but not dramatically so and far less than the BP reading from 5-mapb. 6-apdb also has a tendency to cause temperature fluctuations that can get quite annoying as well as also having a tendency to cause nausea. Personally I never got the nausea, but it's not an uncommon complaint. With that said I find that alot of the side-effects from 6-apdb get less pronounced at higher doses than they do at lower doses.
Now please don't use my doses as a guage for how much you should take as many seem to need far less but an example of the dose and correlation to side-effects would be my first "trip" on it at 100mgs, at this dose there was alot of temperature fluctuation, little euphoria, but a surprising amount of visuals. It wasn't enough to write it off completely but at this point it was definately my least favorite of the four APB's I tried.
I ended up upping the dose to about 150mgs (can't quite remember exactly how much) my next go and there was very little side-effects this time except for some tachycardia. Very euphoric, music was great, pretty damn visual...moreso than all other APB's for sure but like I said before, very little empathy. All in all if your into the psychedelic aspect of these MDA analogues I reccomend giving 6-apdb a shot, just be careful not to abuse these as they are apparently quite cardiotoxic.