Dave, if someone already has REW and a mic like the UMIK-1 with calibration file, is there any reason to spend the extra $ for the CheckMate, other than the convenience of it? I have both myself, since the CheckMate is convenient to quickly check things, but it hardly seems necessary.
As Dave said, you already have the most accurate way available, since the mic is calibrated and much better than anything in any SPL meter. Plus, you can go the extra step and do entire sweeps, which can result in a more accurate level match than Audyssey is likely to accomplish.
Since your calibrated level is close to 0, I'd use the receiver's level adjustment to increase it. If the calibration had come out with it as -10, for example, I'd suggest lowering the sub's level to -40, which would then make the receiver's setting 0.
Many people like the sub juiced a bit. I...