I ran 4.18/4.11 together with 5.12 for quite a while. I actually was receiving a mix of WU's for a couple of weeks on the Asus and the 1.7's. Your numbers are going to be down no matter what. My shuttle was running an RAC of ~350, yesterdays output with the optimised enhanced app was 160. my 1.7's that were running just under 400, are now running around 250.
on another note, the dial up is no longer stressed. Where I was doing 60+ wu a day through the dialup, I am only doing 12-15 now