The general consensus is, you don't know. And I still doubt there is any justification to try to grow a polyembrionic, are the seeds virus free?
http://tropicalfruitforum.com/index.php?topic=12057.0http://tropicalfruitforum.com/index.php?topic=14966.0If you have access to the mother plant, get some scions and graft it (its really not that hard, and it can be done on the cheap). Unless you want to wait a long time and experiment... I started out that way (being very naive about the genetics), now I removed all my experiments. Ain't nobody got time for experiments unless that is your goal. In other words, grow a ton of seeds in a ton of pots, and maybe you get a lot of good mangos, maybe you get a bunch of bad mangos, its a lottery.... but it takes a lot of time and resources over the course of many years to play that lottery.
I think I was on year 3 before I said, hell with this seedling crap. Watering, weeding, feeding...its time consuming and expensive. Just isn't worth it. So in my opinion, the whole poly-vs.-mono debate is bunk. That is just me, everyone has different goals and runs a different race.
Remember, not every child grows up like their parents. How much can you or do you want to invest on chance?
P.S. If you plan to sell to any type of market, consistency is going to be key. And that consistency can only be guaranteed through grafting. You don't want to go to the market and say "most of these are really good, but some of them are not good".