Aye, I think that the gameday should be primarily for playing and enjoyment whilst testing should be for other occasions.
Thats not to say you cant point out flaws in the maps whilst playing, just the main focus should be enjoying the map. (And not just saying 'Next map already'....SOTD!!!!)
On a different note:
In the interest of preserving the gamesdays perhaps more admins should be made for the TF2maps.net server, say more prominant members, so that even if the main site guys arent there it doesnt fall through.
This is pretty much what we do on all the colts playground server, whilst you lot will think of me as the admin for our custom map lab server, there are about 30-40 others and about 10-15 others who have just as much, if not more, power to change maps, kick/ban, start votes....etc. Whilst you might think that this would cause clashes when two admins are on and they want to do different things but it doesn't, we make compromises so that as many players stay happy as posible.