I raid with two medicore guilds. All of them are good players but we are clearly no mythic material (well, a few could manage it quite well with the right guidance I guess).
However, as Highmaul was active with both guilds we cleared 6/7 in three weeks and progressed slowly to 6/7 hc with usually one new kill a week. We spend some time on the imperator normal and downed him eventually. As we started with with imperator HC BRF was released. We continued in the same speed and went to 7/10 normal and 3/10 hc before the itemlevel increase. We spend some time on that damn Oregorger because we learned slow, but whatever.
As the itemlevel increase occured we went straight to 9/10 in both difficulties in BRF and also downed Imperator heroic (because why not?) all in one week.
We tried Blackhand normal yesterday for the first time and I am pretty sure that he will fall in our next visit in the one guild und around next ID or the ID after for the other guild. This will leave both guilds I am raiding with with 1 Boss (Blackhand HC) until 6.2. Wow. And really, we are not that good. We just outgeared so many mechanics.
I totally see why the itemlevel was increased and it made total sense to do it - but the bosses should have been buffed to compensate this. This may sound like a contradiction, but it really is not. You char still gets stronger with the increased itemlevel, just not as much for the current raid.