In my opinion, NDM is an excellent mango eaten mature green. It has tart, but it also has enough brix to balance it out (when eaten at the right stage). It's like a sweet granny smith apple, if there were such a thing.
The NDM #4 can sometimes be very dwarf... which can be a problem for those who don't fertilize. I've literally seen NDM #4 trees die after 6+ years of not growing. And, I've seen NDM #4 trees well over 10 years in ground that barely stand 8 feet tall, with zero pruning. However, some NDM #4 trees do grow just as vigorously as the other NDM's (if memory serves, Zands has an NDM #4 that grew quite bit).
My guess is that there is some rootstock influence that causes the NDM #4 dwarfism. So it's a bit of a roll of the dice, but if you get the dwarfed NDM #4, those things stay tiny.
Splitting is an issue with NDM #4 though...