I have about 4 different montiporas in my tank. All of them are frags that are less than 1" x 1". And I've had all of the frags for about a month. I've seen noticeable growth in one of them, but the rest don't appear to have grown. But that's not surprising for only having had them for less than a month. Except for one that I bought from the LFS, which is around 6" x 6" now, and this has been growing VERY fast. It's probably doubled in size since I bought it 2 months ago.
I have 4 x 250 watts MH and another 200 watts of actinic T5s. I blast all my corals with a mix of cyclopeeze, marine snow, and phytoplankton once a week.