Originally Posted by
Axphyxiate
I recently went through the same transition 3 weeks ago. We were 14/14HM and didn't have super high expectations for our first 25man raid because we had a lot of undergeared players and socials just to fill the 25 spots because we were a few short. In our first week we cleared up to and including Heroic Siegecrafter. We had a few pulls on Paragons but decided to leave it for the following week.
We used our 10man strats for 25 mans and didn't really need to change too much. For Juggernaut we stayed in close-ish to the boss rather than running out and chaining CDs on 10man.
The hardest boss in my opinion is going to be Siegecrafter. This took a night or two to kill. We used a strat where we killed lasers/magnets on the belt and just had the raid stacked near where the mines spawn and just aoe'd them down.
Also I'd suggest turning off non-essential addons and turning your settings down. The input lag when the whole raid pops all their CDs is ridiculous!
Best of luck!