How well does ccPCR indicate the presence of background binders?

I started carrying both + and - protein selected RNA to ccPCR at R3. The ccPCR gel images can be seen here. R3 showed nearly identical amplification between + and - protein. R4 seemed to show a reduction in background binders through the later amplification of - protein selected DNA. Finally, R5 showed nearly identical amplification of + and - protein again. I was wondering how clear of an indicator this is as to the current composition of the selected pool. If we are still performing binding assays after R6, I am not to far from determining the real binding of my pool, but I was wondering if the evidence from the ccPCR gels is enough to go ahead and split of another selection from R4, the round that seemed to show a reduction in background binding.