Gotsc, Not true at all...
I did my I140 at TSC and my I485 was approved at CSC recently. My case was neither faster nor slower than other July RD folks who did both at CSC. Sure, it takes some time for your A-File to travel from the I140 approving center to the I485 adjudicating center. But, this A-File is requested by the I485 center at the time of data entry. By the time you get your FP notice, finish your FP, Background check is complete and your case is ready to be assigned, the A-File would have made its way to the I485 processing center.
But, as I mentioned in my reply to an earlier identical post/thread, there is that extra loop which makes it possible for the case to fall thru the cracks. Having said that I would like to add that the INS Fileroom personnel have enough checks and balances to follow-up until your A-File is procured. My 2 cents.