1rainman, thanks for your post, very interesting, how every location had it s own difficulties. We don't have HLB (and don' t get it hopefully) but we have in z7 sometimes hard freezes, so that in ground planted varieties have to be very hardy, and early fruit ripening as e.g. satsumas.
Up to now we only still know one single variety which has these abilities, the Chimäre Prag, a genetical mix of Poncirus and Satsuma. I have it in ground the 3. Winter but still no fruits yet, first flower this summer. But this variety is susceptible at my place to freeze and wintersun otherwise it gets bark cracks, needs protection.
What I didn' t know and didn ' t test in my place, that Pomelo is hardier than Grapefruit.