The presets are only affected when you go from (say) 3.51 to 4.0. They will be unaffected when going from 4.0B to 4.0.
We had to increase the size of the power-down backup area to hold the larger TF and MF algorithms, and this caused the start of the User Files area to change to make room, meaning that pre-4.0 files can't be found. This is why going back to 3.51 will often make old user presets re-appear, unless they have been corrupted by the new software (depending on what was done before downgrading).
Anyhow, glad things are looking up !!
