I own the BOR since 2 years (DIY-Version), incredibly cheap pedal. I compared to a lot of other OD pedals, but sticked to the BOR, in terms of dynamic response to the playing and mild overdrive possibilies/natural OD sounds.
Since the BOR is a clone of the Z.VEX ROB, I wondered if the Basstortion was the pedal I dreamed of and if it would beat the BOR (even it is VERY expensive here ein Germany). When I compared both pedals with mild ODs (up to 50% OD setting, bright switched, medium output of my Fender 5-string), I found very small differences in the sound. While the Basstortion seemed to respond a very little more dynamically on my playing style and has very little more natural compression, the BOR sounded slightly more "open" which should cut better thru the mix. To my very surprise I can not state that the basstortion has done a better job in the lower frequencies (that was what i expected). I would say that these differences do not play any practical role on a live stage.
I even would say that the BOR switched behind my EBS Multicomp (in Tubesim mode) does a considerably better job than the basstortion (alone). This does not say the basstortion is not a good pedal. It actually is one of the best (non-tube) OD pedals I ever tried, at least switched in bright mode.
I even would definitely prefer the basstortion over the EBS Valvedrive, because it is smaller, cheaper and - in my eyes - does an excellent good job, a better one in terms of dynamic respond to the playing style.
If you own a BOR, keep it, also for the sake of it's very good separate a booster stage. You do not need the Basstortion. If you own a EBS MC + BOR, you can't beat that. EBS + Basstortion however makes not much sence.
If you do not have a EBS MC and you consider to have a very tiny board you should give a try to the basstortion. You can leave it on always, you do not need a compressor, it does it all in one. I would recommend it as a weapon of choice if you just want ONE pedal only (the battery lasts 250 hrs) or need a very small setup to take with you to your practise room. It fits in any bass bag.
Do I keep it? I still do not now. Maybe for small gigs on small stages when I find a "cute" small setup more appropriate: Bass, Basstortion, Combo.
My current (basic) pedal board:
KORG Pitchblack --> EBS Multicomp --> BOR --> Yamaha NE-01 (customized PEQ, but as a pedal version w/ switchable Q-curve and merge function) --> Eden Amp