to add, IIRC ivy bridge is going to be released on 1155 first, so there is the possibility of upgrading at a later date. Buy your hardware for what you need it for NOW. I say go for the 1155 socket and upgrade to ivy in the near future when and if you require it.
triple seems a bit posh and some circles claim that its just not good enough and i think the max support is 3 by 2gigs or 4 by 3 gigs correct me if i am wrong...
where as dual channal can be taken all the way to the mobo's max(depending on board) 24gigs or so on