I like the concept of hybrid units very much. I think, however, that the 10/90 battalion has an inherent weakness that makes it unattractive to the Reg F.
If you look at a 10/90 infantry battalion with a full-up strength of 6-700 it means the Reg F component is approximately 60-70 personnel who the Reg F in general, look at as being heavily underutilized on a day-to-day basis and potentially unavailable for deployments. With a Res F as small as 20,000 that still adds up to 2,000 Reg F personnel (add another 3-500 for brigade headquarters) who are "lost" to the day-to-day operations of the Army with their only perceived benefit being the eventual creation of a useable battalion for a major emergency. It will always be a target for syphoning off personnel (and equipment if its ever given any) as "more important" missions come up.
I would think that what might perhaps be more palatable to the Reg F side would be a hybrid battalion of say 25 to 30% where much of the battalion headquarters and one full company, squadron or battery would be Reg F. The reason for the full sub-unit is that when not conducting reserve training, it would have a sufficient mass to train itself and provide continuous career development for it's personnel. It would also be sufficient numbers so that during the very busy summer training periods for the Res F elements, there would be sufficient people to allow for a reasonable summer leave and APS program.
More importantly, as a complete sub-unit, it would be available for deployments (assuming it could raise sufficient augmentees from the Res F component of the battalion to leave a large enough core behind to continue on with the rest of the battalion's training). The same would be true for the battalion headquarters. It could do occasional rotations so long as a sufficient core remains behind to lead the entire battalion. In fact a properly constructed system could create more deployable unit and even brigade headquarters and thereby create not only more deployable "chunks" out of which task forces could be formed during peacetime but also create a viable framework of a force which, in an emergency, could form a larger force then we now are able to generate.
The ratio of Reg F to Res F ought to be somewhat flexible so that units with a high peace-time day-to-day utilization or deployment rate could have a second Reg F subunit while those which have virtually no peace-time day-to-day utilization could have a smaller Reg F component.
As T2B points out, it's weakness within the Res F perception is the fact that it does negate the need for senior Res F leadership. Essentially there is no need beyond company level majors and MWOs and, perhaps, a very limited number of LCols and CWOs. Quite frankly, and notwithstanding D&Bs experience, the system could and should be developed so that all admin functions devolve onto the Reg F cadre and that the only responsibility for the Res F leadership is the training within their own companies (with opportunities to voluntarily rise into battalion or brigade staff positions if they accept the required training)
I must admit, that the regimental system with its tiers of leadership and special buttons and bows creates a problem with this as Reg F and Res F are all bound to their cap badges. I'm somewhat envious of the flexibility of the US uniform system which is fairly standard and battalion identity is portrayed by a single enameled badge worn on the chest with brigade or divisional affiliation by a shoulder patch. It makes cross-posting dead simple. That said, I'm sure that we have enough CWOs in the Army who can sit down and work out this particular conundrum and do we really care if on a battalion parade one company parades in a highland uniform and another in rifle green? I guess the QM might but that's why he gets paid those sweet, sweet Reg F bucks.
