Yep good choice - but I have a few additional comments I'd like to add to Darin's,
Recall that your velocity t3 is going to be leaps and bounds ahead of the MAG in terms of quietness. The other thing you should likely consider if you are going with a sub. pump is heat exchange. Typically you want to keep this as low as possible and a MAG 12 is likely to add a degree or maybe 2 or three to your current water temp. This may not be a problem if your tank is in a very cool spot but if it is in a living area this may be a concern as so many things already add heat to tanks.
I'd recommend that you try to use an external return, there are plenty that will do this job quietly, effeciently and with little or no heat exchange.
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein (1879-1955)