I can say this, as an active user, and a moderator on 2 sites now.
It is entirely possible to be a moderator on a site and not be very active on it. I have been a moderator at Graphic Design for a year now. During this period of time, I have asked/answered about 5 questions, gaining maybe a few hundred reputation. I would like to think I've done a fair job at moderation. But only fair really.
To be a moderator, one needs to know the site inside and out. They need to know what is on topic, what is off topic, what is general reference, and what is a good question. They need to participate in meta, chat, at least to read and take part in policy decisions, but they will be better off if they are actively contributing to the site.
I have recently been voted in as moderator of a site that I am quite active in, and have been active for a year, namely Science Fiction and Fantasy. It has made a huge difference being active in the site, and knowing what I need to do to help make it better.
While I can and will continue on as a Graphic Design moderator for so long as I need to, I feel like I would be better off if I cared more about the community.
So, I would suggest raising the limit to at least 2000, and quite possibly 3000. At least a 3000 user will have had to think about closing posts, which is one of the most basic things a moderator needs to do.