With Mythic raiding going to 20m in WoD, we have been in talks with another guild (withholding the name in case it all falls through) about merging our 10m teams.
I've always been amused by merger dynamics - everyone always tries to impress everyone else and tiptoe around each other; people are worried that they won't fit in and vice versa... it's pretty exciting and nerve wracking for everybody.
I would have to say that I'm more excited/wary than nervous, myself. The guild we are thinking of merging with is higher on progression than we are, but I'm fairly confident in my ability to at least be adequate, if not brilliant. Pretty far cry from half a year ago when I was about to join a heroic guild after a) being rusty on skills and b) leaving the guild I had been in for the past 8 years.
Since this is the 3rd new guild I would have encountered this year, I suppose you could say I'm even used to the process... never thought I'd be in a situation where I'm one of those heroic raiders that jump guilds to stay ahead - and I certainly don't feel like one - but from the outside it probably looks that way! :P
At least this time I won't be doing it alone; most, if not all, of Zero Yard Range are looking forward to Mythic raiding in WoD and barring any serious personality clashes I can't imagine why the merge wouldn't work. Interesting times! :)