STH,
I was an FSC on 643 from mid-87 to late 88 and your tale seems very familiar!! Do we know each other?
At Scampton 643 and Humber GC ran alongside each other in those days and as I recall it worked OK (apart from one or two peoples' antagonism). So no reason why VGS's and the RAFGSA can't co-exist, as always it's down to the people involved.
And IMHO the ATC is money well spent.
Jobza