I've now got it set up with a .conf file and running kalroth's 3.7.2 cgminer and can't get as high of a hash as I was getting before without the xintensity. I think my card has 2816 shaders so the xintensity would be 372?
Try bumping it up a good chunk, say double. Personally I didn't have much luck with kalroth's miner, even though it has the same xintensity code as sgminer. 372 makes sense by my math. I use 1100 on my 290 (non-X).
Also set your tc to a multiple of 2816, and then add or subtract 1 to see which gives more efficiency (usually adding 1 will give you a bump). Say, 28161 or something. xintensity means you don't have to push TC so high to get the same performance, because you are aligning the number of threads launched with the number of threads you can actually run at one time.