Thanks for your kind words and sorry that your name has never appeared on the Most active list, take some solace in the knowledge that we notice you here .
The most active list is not a very good indicator of site activity as it seems to show new users and only a few active users as you mention. In the past we have attempted fixes to update the section more frequently but alas it still frustrates. Be heartened to know that we are looking to upgrade the whole platform very soon to make the platform quicker but also add some more nifty features that i will mention later today in a blog post.
As for the rating functionality, we utilised the photos side of it more acutely than the forums side by adding a highest rated/most commented/most viewed feature on our images page, but you can still see an indication (from you the user) on the quality of replies on a certain posting. To recap, one is poor and five is excellent.
I hope this helps.
AirSpace - more than just hot air