Having experienced treatment at both DKPH (well actually Nuffield Trust Newcastle due to lack of space at Catterick) and at the Priory I feel I am perhaps qualified to speak on this subject.
Whilst it is true that as a serviceperson many would wish to be treated in a service environment it is also true that many service personnel don't wish to be uprooted from familiar surroundings and despatched off to a windswept garrison at the ar$e end of the country in order to seek treatment. The move to treatment by the Priory group was aimed at preventing further disruption to personnel under treatment as they could be treated more locally. The quality of care offered is also of very high quality and they are not purely drug addict clean up clinics.
On a personal note though I found the cognitive therapy offered by DCMH Brize Norton of the greatest help and will always be truly grateful of the assistance they gave me overcoming my problems.
Whatever is spent on mental health treatment for service personnel is not enough. As I have said before on the subject, we in the military will laugh and joke with someone who has perhaps broken their leg etc, sign their cast and listen over and over again at the story at how they came about it but we shy away from those who have through their service become broken of mind (a far easier thing to break than any bones) and it speaks volumes of how we as a humans shy away from what we don't understand.