i think it might be worth it, depending on what you are using your computer for.
Switching to 2011 for a bit, i've seen some benches.. (umm.. still nda, but from someone who has it lol).. in some single thread application it is slower than sandy.. maybe due to lack of proper microcode, or bios optimization. Arch isn't that much different from sandy tbh.. so i don't even think it is worth it for the average consumer (unless you are benching, or need a workstation)
back to 1366 to 1155, you will get an increase in clock per clock if you do move to it. Benches like 3dmark11 will see higher scores (however vantage will be better served with more threads, so westmere/gulftown win usually). They will also generally clock higher than 1366 on air/water. More efficient cpu overall... less power consumption... upgradeablity to ivb in the future. Only thing i really don't like about it is the lack of scaling under cold/ mghz wall. I don't know if intel inherently made this appart of their design or if it was a effect not purposely caused.
Sorry for the long tangent.. but yes, i generally think you'd be better served to upgrade now taking a look at what is out there, or at least what will be out there very soon