I have a tree growing in a container, that has not flowered/fruited yet. most reports by people that have tasted it, say its average at best, and not worth the space, unless you have a lot of space.
My tree has grown well, but has shown susceptibility to powdery mildew at my location.
may i suggest a Keitt?, there normal weight is around 1.5-2 Lbs, but there was a record breaker Keitt in Hawaii, that tipped the scale at 5lb 7 oz. so if your looking for a big Mango, go for Keitt, at least i know that variety is decent, very productive and relatively disease free.
I am still waiting for my Lancetilla to produce its first fruit, if its lousy, I will top work the tree, if its just ok, I may leave a branch, just to have the genetics around.