As a candidate in the election one of my concerns was my apparent lack of Meta participation. However, that doesn't mean I'm not aware of what's going on, just that for a lot of things I'm not going to waste time trying to FGITW more active and experienced users when I know it'll be answered perfectly well and I could be spending that time editing posts into shape etc...
A comment on my nomination post which shows one way of looking at it:
"keep up to date with Meta (even if I don't say much that often)" It's nice that you have a processing type of personality. The community would greatly benefit from a guy who devotes more time thinking on what others has to say, where instead of words he puts his resolve on those discussions on proper actions. - Mark Garcia
But I'm sure others would look at it from the polar opposite.
Unless there's something that needs my input, or there's something I feel strongly about, then I just observe as if I can argue both sides equally well, then there's no point creating noise with my neutral 2p.
So while I agree with Brad that Meta participation is important, it's difficult to quantify to any reasonable metric. I'd be wary of someone that'd just scraped the Convention badge, but at the same time, I'd be wary of someone that was answering every single Meta question they possibly could (as they'll have to learn to step back to do some exception handling instead and let the community answer).
I personally found when voting that comments were useful - even just the way people ask for clarification, or point out faux pas that new users have committed is an indicator of their attitude which would probably carry over to Meta posts should they have to handle requests/justify their actions.
So yes, while it's important, and I was very wary that a lot of people would weigh it very heavily in their decision, a balanced approach is more reasonable - and for me that was trying to get a feeling for attitude and consistency rather than Meta rep.
Bottom line: People will choose on whatever basis they wish
(further eg: I did see some Twitter posts where one person was voting based on people that used their real names and another for the people with the "coolest" avatars...)