I've had my ProTank going for about two weeks now. I had some gripes in the beginning, but none of them dealbreakers and some have become non-issues after a few days of use. Ended up grabbing a second one yesterday.
I'm getting great flavour and huge puffy clouds with a 50/50 mix, no messing around with the top wicks needed. The coil is still going strong, no burnt wicks, cleaning is a breeze (and you can dry it easily with a little paper towel if a thorough air-dry isn't convenient) and has an even cooler hit than other plastic BCCs I've tried (something I prefer).
I do find it lacking for higher VG juices - strangely, I've found the T3 outperforms the ProTank for 70% VG juice. This prompted me to try removing one of the top wicks... lo and behold, the gurgling and leaking issues reared their ugly head.
Bone stock, she's a solid performer and quite versatile. I can see how it won't be everyone's cup of tea, but I would think that would be a common thread for wide-body BCCs in general.
Oh, and as a final note, I've noticed the flavour does get better over the first few refills. I'm theorizing here, but I think the steel and glass needs a little bit of "seasoning" as there's a kind of sterile flavour imparted on the vapour right out of the box.