I am in a guild that has been running ten mans since BC, and we got some good progress in ulduar but are having problems getting consistant members. I play almost every day, but most times we have only a few online, not enough to even run a heroic. When raid time comes people show up, but lately we will be one or 2 short and have to call the raid. They have tried recruiting but there are lots of guild recruiting and its hard to find people for ten man raids when twenty five mans are recruiting next to you.
Its annoying because we never get anyone online unless its a raid and then when we call the raid noone stays on so we can't even do anything else like naxx or something.
I don't know if i should stay or start looking at other guilds. Most guilds dont need tanks though and i dont want to be dps or healer.
In my guild we have a similar problem. Though we aren't up to Ulduar standard yet we were doing OS and VoA reliably (admittedly it would help if more members understood Naxx, and so don't think we've done a guild EoE run). If you want to raid reliably, then I suggest you should look at other guilds; if you're after a more social aspect (ie casual raiding) then try and stick with both the guild and recruitment. There are people out there who aren't all hardcore number crunchers; though it sounds a little odd there are people who play the game for fun, not just to do Ulduar 25 every week to get the best gear.
As I said before, decide if you are happy in the guild (look at unrelated guild events/ problems) and then make your decision.