There aren't really any advantages to going 1156 now unless its just a cost cutting thing. Even then, 1155 chips are quite affordable given the performance you're getting.
The difference between 1155 and 1156 is actually pretty large 'unger-the-hood'. Especially with regards to memory management and moving the graphics on to the CPU die. 1155 brings a lot of advantages to the table. The on-die GPU in 1155 CPUs are better than 1156 CPU's motherboard onboard chips. It manages data better and is really straight up faster in every way, not to mention its enormous over-clocking potential (for -K series chips).
A lot of good things can be said about the 1155 chips.