All depends on the guild experience.
In BC my guild was "just there to do raids" so all I really cared about was progression...but then I burned out in the lull between the xpacs
In Wrath I found a bunch of people I got along with...they weren't as hardcore as the BC guild (I guess you would call them Hardcore casual) so we progressed slowly but it was fun cause of the people
Missed Cata, but now in MoP I found some older HC raiders that just don't have time anymore cause of life...so we raid 1/w for 4 hours. Progress is slow...but its still fun.
We hit the Horridon wall as we only started raiding 2 weeks before 5.2 (and some of us only got to LFR 1 or 2 weeks of 5.0 content)...we went back and cleared the last 4 of Heart and TOES before we went back into Horridon and it helped a ton. Probably only two weeks....the iLevel increase was all the help we needed. Remember at the time only the first 3 of LFR ToT would have been available...so that was the only gearin option.
We are all fully normal decked now, so I don't expect to go back...but assuming we had to, I'd guess we would Flex it down first before going back to previous...at least till LFR was released to fill the gaps.