I think a better analogy for the Protector's Own would be to say they're like the Blair Atholl Highlanders, only fully equipped and trained like a regular military unit. In fact, they seem to regarded as something of a elite, highly motivated unit that demands and gets performance higher than the regular GSN (see _A Ship Called Francis_ and _Obligated Service_ for standards that the GSN is prepared to put up with). (The best of the GSN seems to think it a point of honour to show that they're just as good, the worst of the GSN seems to think the PO are total loons who spend too much time in the simulator and/or doing live-fire exercises.)
The GSN seems to maintain itself as, practically, a well-trained, elite navy, by isolating its slackers and embarrassments where they can't cause much trouble.
The RMN occasionally makes them First Lords of the Admiralty.
The SLN will get good, conscientious officers off flagships and ignored at ONI whenever they show their ugly faces.
Soooo... overall, the GSN may be doing pretty well handling personnel issues.