We full time in a 2552 so I can't tell you specifics on the 2910 but I can tell you why we didn't buy it. The longer rigs with more windows REALLY called to me and I agonized over the choice for a long time. We wanted to stay under 30 feet so we fit in the older campgrounds (negligible, I know). We also worry about weight/payload. When I pressed him, Kermit estimated I'd lose about 1000 pounds of available payload by going with the extra slide. We only have 3000 in the 2552 and while that seems like a lot, it isn't. You have to count everything: fuel, water, propane, food, clothing, tools, dishes, and on and on - don't forget the people and pets. It adds up fast.
We are very happy with the 2552 and think we hit the "sweet spot" with livability, drive/handling and the all-important payload. But remember, everyone is different. You have to make a list of pros and cons to see what works for you.