One of the biggest myths in this hobby is that there is such a thing as an 'sps coral' and that it needs high light and high flow.
Dr. Veron tells us that M. digitata can be a dominant coral on mud flats. This is not a high flow environment
Another problem. Which montipora. Again, according to Dr. Veron, it is the second most abundant genus in terms of species. No doubt they occupy a wide range of habitats that cover a range of water flow conditions.
I kept M. digitata in a 650g tank with a flow of 750gph, not a particularly high flow tank. The coral was not even loacted in the highest flow area, yet it grew quite quickly.
Here is what I would do. M. digitata and plating montiporas like M. capricornis are very common in the hobby and not particularly expensive. Get a small frag of which ever Montipora you are looking at and put it in your tank to see how it does.
Fred