I found this bus to be a fairly smooth ride, it didn't seem as juddery as the E400's Arriva use on the 7 that I am used to. I found the bus performed okay in terms of performance however going down the A1(M) it has to be said it didn't feel that fast, don't get me wrong it wasn't slow but it didn't feel like it was thundering down here, it's possible that it could have maybe gone faster and this may have just been the speed the driver chose to drive down the A1(M). Didn't get much experience of it on hills as there actually isn't that many and when we did go up them we had roadworks and traffic so that slowed us down a bit. Overall I thought the performance was okay.
In regards to the interior I thought the seats were extremely comfortable, even the one at the front which is a sort of a bench was pretty comfortable. Wasn't sure about the heating / aircon, if you were sat on the front seat on the drivers side upstairs the aircon would give you a cool head. Unlike some Enviro 400's there was no rattling or anything like that.
Overall I quite enjoyed my ride on this and think they would do alright if they were bought for this service... although we all know that the X21 is getting the Red Arrows B9s
