Main point first. LogBlock doesn't track entities. Therefore, LogBlock doesn't track things like item frames, paintings, etc. whereas CoreProtect does.
CoreProtect also tracks water, lava etc. so if a person uses water and/or lava to grief, it can be rolled back, just by using "#water" instead of a user's name, for example.
Obviously, LogBlock is replaced, it would not be possible to rollback anything that happened before CoreProtect was put in place.
Therefore, my recommendation would be to keep LogBlock for a short while whilst CoreProtect is in place for a short while.
Hoping at least some of you agree with my opinion here.