There are plenty of 775 boards that don't support any cpu's beyond a pentium 4.I would think for testing you would want a modern 775 board that supports newer dual core cpu's also.
That's funny because a lot of sandy bridge owners use too own 1366.
Worth it?For most gamers no,but everyone likes the overclocking performance.
It's when your computer can't do what you want it too,when it becomes worth it.
Yes it does sound ok but does it warrant a price increase when a 2600k owner is going too overclock anyway?
The overclocking potential will be the deciding factor.
Spending the 200 bucks or so just wouldn't make sense today when a 2500k can be had for the same price.Even if you do have too swap your motherboard.
A good p67 board can be had for under a hundred bucks now.