Are you looking for two trees thinking you need them to get avos?

home growers don't need an a and b to get enough fruit for the home grower.

sorry don't know anything about your choices.

Utuado has been compared to Catalina. I have it on my shortlist of maybe's. Go to myavocadotrees.com. Carlos is a grower in miami and has more info on every cado than any other site including utuado. Tim is right don't get too hung up on the A/B pollination thing for just home use.

take a look at Brogdon and Oro Negro also for Hass type of flavor. Both are cold hardy for 9B.

I have a video that may be of some help. They do well in fast draining soil, yes your sandy soil will do well. They will do fine in partial shade.