Peter....The two systems I have;
156 gallon display with 100 gallon sump/refugium, has MR2R on it AND
an older ASM 4
and
175 gallon DT with 75 gallon sump/refugium....MR2R and ASM 3
I felt that I could not 'overskim' so I continued to use the ASMs once I had
hooked up the MRs. I have not tried the MR2 alone on these systems.
BEFORE the MRs were added I had an ASM 3 and ASM4 on each system and removed one of the ASMs when the MRs were placed into service.
Hope that helps. My opinion would be that in a moderately stocked 210 you will be very happy with the MR2R.
Andy at MRC is very helpful if you call.