The point about why are they using the same FTOs - it won't be to do with the standard of training received, it will be more to do with the candidates themselves.
Also, there are only so many FTOs with a proven track record of the Integrated course. BA has put candidates through Oxford since the 1960s, FTE since the 1980s (when it was BAe at Prestwick) and used CTC in the 1990s for Jet Orientation Courses so there are long standing relationships which each.
For "low houred fATPL holders", the DEP process will continue. For CPL holders, I can verify what moo says. A CPL will disqualify you from this scheme. Sorry.