Just buy the best amp(s) you can afford with an appropriate amount of power for your needs. Mono doesn't automatically mean magic, it means separate left and right chassis and the imaging will be better, everything else being equal.
The MC402 runs around $4500-4900. Just get the best amp you can find in that price range. @normantaylor liked the Magtech amps better not just because they are monos, but because they are better amps and they really lit up his Maggies.