The last two updated estimates of what you should expect are more accurate, I believe the numbers you heard before (~50KPPD) were from before the bigadv points were adjusted (lowered
I would not tell you to stop folding on your GPUs, the can kick out a good amount of points, my 580 folding gets along just fine with my bigadv folding and kicks out about 19K PPD of it's own. What I would do for your GPU's is have them run the -advmethods WUs which eat up less CPU cycles and should actually give you slightly more points on the GPUs as well as the increase from your CPU being able to focus more on it's own folding. Post back with what client you are using and I'll be able to tell you how to set up the advmethod WUs.
There are potential downsides to the advmethod WUs that you ought to be aware of, mainly that they run about ~10c hotter on average than the regular WUs, and are much more sensitive to exposing instability in what you thought was a stable GPU OC. In my opinion though they are well worth it for me even with just one GPU folding, and they should be more worth it for you with 2 GPUs folding. What GPU drivers are you using? There have been a few different problems with the more recent ones that I want to make sure you avoid, I recommend the 266.58