For anyone interested i'm going to post my trials with getting -g 2 or gpu-threads 2 working on 290x. I have limited trials on the 290, but ran into similar condudrums there as I did with the 290x below. I'm trying to lower stales/rejects on scryptguild by using g 2 and lower intensity while remaining near peak kh/s I get using g 1. Haven't found a solution though.
Due to how picky g 2 is for the 290x I had to use xintensity instead of intensity. This requires sgminer 4.1.0 or other non classic 3.7.2 cgminer.
With xintensity set to 4 or 12 I got the best resutls with TC set to 11264 (4xshaders) or 22528 (8xshaders). For the most part with g 2 everything else I tried gave hardware errors or was much slower. This never got me closer than 70kh/s from where the same mem/core would get with g-1 and intensity 20. So for example 900c/1250m with g-2 and xintensity 4 tc 22528 would give ~780kh/s and <1% rejects wheras 900c/1250 with g-1 and intensity 20 tc 22528 (or 33793) would give 850kh/s but with ~7% rejects.
Using intensity <18 on the 290/290x really slams my kh/s so simply sticking with g1 and lowering intensity doesn't do much good.
Still going to fool around with it, but if anyone has been down this road or wants to join up, let me know what ya find.