Hey Simon,
It seems you really like Keitt taste. I noticed you had the opportunity to taste many kinds mango at various events, and so do you consider Keitt is on your personal top 5 list? My taste is different that I prefer strong flavor mangoes like NDM, Okrung, Cac Hoa Loc over Kent,Keitt, Glenn. Especially I find Keitt -- even local grown in CA -- too watery, enough sweet but no flavor.
(I have not tasted a NDM (not NDM golden color) but read from a Thai poster that he preferred NDM over Okrung which I had some fruits this year and I rate it at top of my list as of today, and so I think might like NDM too.)