According to what I have read on the Golden Queen, it seems to have good disease resistance.
as for marketing, I understand that having something exotic to sell to a niche market at a higher price can be a good idea, specially when the market is already flooded with common varieties.
but one has to take into account that those common varieties are popular for a reason, usually because they produce well in the region, and have a flavor preferred by the majority of the people.
If you can get popular varieties to produce outside their normal season, you can get a lot better price, so this is another option.
there are so many disease resistant varieties that have commercial potential, Rapoza may be an excellent mango in Hawaii, and may or may not do well at other locations, but will it have a flavor that your market will like? I have only tried a few Eastern type mangoes and have noticed they seem to have a stronger or different flavor than American types.
If you have noticed in this forum, people have a preference for certain varieties they grew up on, the Aussies love their KP, Hawaiian Rapoza, in Mexico its the Ataulfo, in the Dominican Republic, the Banilejo. and on and on. to the locals that grew up on a particular variety, its that variety that they use to measure and compare all other varieties they try.
As an example, Banilejo, is a small slightly fibrous mango that is very sweet. and is a favorite to locals in the DR. give someone a Kent or Haden, and they find them bland in comparison. another variety is the "gota de oro" this is the second favorite, and it is like eating a mop soaked in sweetened mango juice. Keitt is becoming popular now, because it has a decent strong flavor, and farmers love it for many other reasons.
My solution is to collect about a dozen popular commercial varieties and then test them with people to see how they will do. since Dominican seem to have a preference for intensely sweet varieties, they may actually love varieties from the east. So far I have Kesar, Alphonso, Maha Chanok, Manila, also have the new Zill varieties, except Angie which I still want to get. also want to get the Golden Queen, and a few more like the Sindhu, Xoai Cat Hoa Loc, Cat chu, Chausa and Neelam
I will be testing, Rapoza, Osteen, and a couple others as potential export varieties. who knows maybe there will be a market locally for them, not everyone has the same tastes.