Just a note on the specialty training available or open to reservists; I know of one unit in particular that has 10 Basic and 2 advanced mountain warfare qualified troops. It also has 3 Close quarters Combat instructors, 7 Recce Patrolman 2 Advanced Recce patrolman. It has 5 Urban Ops Instructors and 12 Advanced shooting Instructors.
The point of all this is that the training opportunities a there, it is just a matter of having the right people, who know how to make the system work the way it can, as well as be willing to up up the money or make the troops available to do the courses.
Good working relationships with a Reg Force Unit certainly helps.