I have never really looked at gerrit in detail, but if my understanding is correct, it requires the use of a web-based interface?
I really hate web-based intefaces, as they require an online connection. The way how I read and process e-mails is store-and-forward, and I often work on them while I'm offline (in a plane, on a train, ...)
It's not that I'm not particularly known for doing most of the review in recent years, but I would consider a move to mandatory use such tools as somewhat of a step of "alienation" between the project and me. It's not that the number of submissions we're getting (at least so far) is _that_ lage that it's so easy to loose track of them.
Rather, there are contribuions that are not merged as a) there's not sufficient time for senior project members like Holger or me to review, or b) the original submitter is not followin up (quickly) adressing changes by the maintainer(s), or c) code that exists in some branches which is never submitted to the list in the first place
I don't expect any tools to help with the issues above :/
Regards, Harald