I was able to fit a compression fitting and a 45 with a compression fitting on the side ports of my MCRES, with the Bitspower o-rings. It seals up just fine. The ports on the res are recessed a little bit, enough to be felt with my finger, but the o-rings seal up fine.
As far as the pump replacement tops, I really like the Bitspower one at Sidewinders, which didn't seem to be in Skinnee's review. I could be wrong and just didn't read thoroughly enough, but the last time I read that review, I was pretty pressed for time. One of these days I am going to order it just so that I can use my compression fittings on the pump as well as the rad and res. I have Bitspower True Silver fittings for my blocks, which will help keep the nasties out of my loop. If I notice a problem, I will probably buy a silver strip from JT and make a kill coil or two.