I have the ARB 2500, I have both the early and late rooms to go with it, there are pro's and cons for both rooms.
Early room, windows zip down but not across the bottom, blows a hoolie in there in the slightest wind. There is only one exit point which isn't always convenient.
Late Room. multiple exits, zips on everything, mosquito nets on everything too with zippers. wind dont get in but leaks like a collendar through the zips.
The awning itself can be setup in less than 2 minutes by one person, great bit of kit. Now that stockist have replacement poles has made it a better choice.
The only real fault I can pick with it are the strength of the aluminium poles, not very strong when pulled out to the 2500mm.
ARB also sell side and front windbreaks for these things.
A small design flaw is you cannot have the front wing attached at the same time as the room ....unless you add an extra C channel to the front edge.