This is what I have tested it out:
I have been out of the loop for I waited out for a few months to see if anyone was going to root 2.2.2 but decided to downgrade to 2.2.1. After doing so, I tested out the 3G with 3020 (keep in mind I live in Hollywood, which is between Fort Lauderdale and Miami) but no 3G signal. Then I went to 3022 and that signal is more widely available from Doral up to some northern areas of Fort Lauderdale. 3023 has some signal strengths but it's very weak unless you are in the south border of Broward County and most of north Dade County. 3024 so far has not given me a good confirmed signal anywhere in Broward but has not tested in Dade as of yet.
My best suggestion is to stick with either 3022 or 3023 for it has a higher rate of success in receiving 3G but as for 3020 I believe that it might be obsolete and as of 3024, it is fairly new so maybe not too many areas responds to that code as of yet. Maybe someone might be able to confirm this for assurance?