I don't grow them in pots, but they do look a bit small to take a severe pruning. You wouldn't want to get down too close to the graft.

I have been growing four mango trees that I bought in Rays Nursery, for 5 years now. Obviously I am not an expert but your trees look so small and tender. I would transplant them into the ground or a larger put and resist the temptation to pruna again.
What I have found is to wait till the tree is in the ground 2 years, then give it a vigorous pruning and tip snipping. This opens up the center so the sun can get in and starts the tree off with a general shape. Then two years later do a minimal pruning, then let the tree alone indefinitely. They are very hardy ( except on 30 degree nights ) and will accept an agressive pruning, they recover fast.
Am sure you will receive lots more advise, this is just my two cents worth. Good luck !

You need to prune when they are young to get a more bushy tree. Fairchild Tropical Gardens has some great videos on how to prune young mangos. Here is one link.

http://www.youtube.com/watch?v=S_4_dQgG2s4

Here is a link that might be useful: Pruning Mangos

Well, I had my clippers out doing some trimming of my other trees in preparation for the storm and I couldnt help myself...the mangoes both got chopped. I hope i did the right thing, but I guess time will tell. I get some shots up soon for more opinions.

Thanks!
Ice Cream