I have a recently planted 'Ruby Red' and a Thai-White.
The 'Ruby Red' gets infested with the fruit fly, which is a shame because it's not just a great tasting fruit, but one with a beautiful red colore (inside) too. If the '10-30 Ruby Supreme' circumvents this, then I'll suspect that I'll be getting it.
The Thai-White guava tree has no problem with the fruit fly worms, it's just that so far it hasn't been been very productive and it does have some sooty mold on the leaves.
I love guavas, I love the taste, they are fun to eat, but the problems that I've been having with these two varieties is just no fun at all. I'll be doing something to shake them up a bit, but I just don't know what. Maybe I'll be fertilizing them heavily with dog poop and vegetable/fruit leftovers. I'm also considering propagating them from seeds.