Even in Japan where Irwins can be marketed as the "egg of the sun", they are poorly flavored.
If flavor is a priority, you can skip Irwin.
Ok, so apparently they have no idea what a great mango tastes like. 
I couldn't agree more.
Hi guys, I see there is not a lot of love for Irwin mango's in your parts of the world, but did you ever taste Irwin mango, right in the season, from the source in southern Taiwan?
I am certain that this would change your opinion.
The same mango grown in different parts of the world, is never going to taste the same in each place(climate, care,soil). The love and care people put into growing the Irwin mango in Taiwan, among many other varieties, pays of in its taste.
Don't run into a supermarket in Taipei at any given moment of the mango season and buy a mango there, know your source and buy them when they are in the season.
There are also Florida mango's here which are just not grown as much as Irwin or others, and you can taste that in the fruit, they are far from excellent here! (for example, Keitt and Haden mango) But I am sure they taste great when you get them, and eat them in Florida.