Whilst it would be good to have the E175 based at Southampton, there wouldn't be enough room for one in the summer unless it replaced an Embraer E195, which is unlikely given the amount of summer routes it will be doing in 2012.
I think the aircraft stands need to be re-arranged first, maybe we'll see them based in 2013?
There would be enough room, the 175 can use the Dash stands, it's dimensionally smaller:
Dash: 32.81m x 28.4m
175: 31.68m x 26.00m