I think the best thing for them to do would be to save our Grimoire and all that stuff (like the Grimoire enemy kills ranks) but wipe our characters. They could save our progress on the dead ghosts (as part of the Grimoire, because they basically are), too. Basically, this would mean that we don't have to go through the tedium of going to specific locations and accumulating Grimoire score (this stuff isn't tied to individual characters anyway) but since their are plenty of good arguments either way for the gear, I think they should just wipe it. I'm sure many people would make different decisions in the full game after playing the beta.