Well, it's all down to just how annoyed you are by the terrainI've got a little bit of biome replacement chunk errors after updated from 1.0.9 (after world was gen'd in 1.0.8 with the horizons ATG.cfg) - would you recommend regenerating the world? Just really annoying to have beautiful landscapes ruined by absolute sheer cliffs at the edge of the chunk as it goes from highlands to ocean.
I'm a little bit too keen on jumping on these packs before they hit recommended I think
Using ATG, BoP and Highlands.
Depending on how much area was affected, you could try to terraform it, maybe make it look like the chalk cliffs at Dover of something. If it's too much to do that, a reset might be your best bet.
It was hard not to jump on the beta versions of these pack... I was champing at the bit for some 1.6 FTB, so I just went with it.