I'm still using my OG, so I can't verify this.
As I've read it, the problem is once the 4g phone tries to either transition down to 3g or up to 4g it loses data completely and you have to either hit airplane mode, or power cycle.
Apparently this doesn't always happen, but it does happen. I've read it happens with the Charge, Bionic, Rezound and Razr. Some people don't seem to have the problem at all, others have it occur every day.
I have read some people who got the Bionic update recently have seen an improvement in their data loss, but this was maybe 2-3 people so definitely not enough to verify the problem is software related.
My guess is the 4G towers are still causing some issues between data transitions.