Tough choice. The QHY9 is on special this week and includes RGB filters (not sure which ones). SBIG is not available yet.
Does that swing it for you?
I wonder if the effort SBIG is putting into the ST-8300M + new filter wheel has delayed the STX range?
Next job for SBIG (or QHY) should be a lowprice KAF-16803 based camera.