These threads seem to end up getting locked lately, he is my opinion having used both products. I'd use one or the other not both at the same time. I prefer MMO for cleaning, now that I've had plenty of time to base my opinion.
If you want to use both products this is how I would do it. Since you have 900 miles left to this OCI add a pint of MMO. Then run the A-Rx clean phase for 5000 miles using dino oil as they suggest. When you do the rinse phase run a pint of MMO for the last 1000 miles of that phase. Use dino oil again. IMO you have a better shot of cleaning up varnish this way, and really disolving sludge. This also seems to be the opinion of many others.
My intention was not to start a flame war. So guys this person asked a question, I've used both products and offered my opinion. Take it for what its worth please, and with an open mind!