To add a bit to the above post, generally speaking, the QHY8 doesnt benefit much from dark frames.. The inherent noise is just so low that it makes the effort to take darks seem like wasted time..
If I had the money to put into it, I would definitely be looking towards an SBIG, as lets face it, they are SBIG
However, given my budget, I went for the QHY8 and can honestly say I've never regretted it..
I've also been looking at the Starlight Xpress cameras recently.. and some of them look to be very good also.. Although they seem to be very expensive for what they are... The SXVF-M25C has the exact same imaging sensor as the QHY8, yet the QHY8 is around 1/3 its price. Seems hard to justify to me..
Another thing you might benefit from greatly with your setup is Adaptive optics. A lot of people think that this is an SBIG only pleasure, however Starlight Xpress make an adaptive optics unit that will work with any camera.. You just need to use a Starlight Xpress guide camera with it.. I'm currently looking into the SX Adaptive Optics unit for use with my C11 for imaging.. as the affects of seeing become very noticable imaging at the longer focal lengths..