I'll make again the point I made on the other thread. With the odd exception, most ATCers will grant transits, provide services etc to GA. In many cases, they go well beyond what they are required to do.
In most cases, the reason they will refuse a service or whatever is due to the effect of a particular policy decision taken much higher up the food chain. Eg not funding LARS, setting Class A too low, not maintaining the radar heads, not building in any slack to the system etc.
So, IMHO, the issue is not a deteriorating relationship between GA and ATCOs but between the community (the ATCOs and the pilots) which have to apply the policy and the community (DAP, CAA, NATS, EASA, Treasury etc) who write the policy.
No harm in GATCO meeting up for a chinwag on the issue but I just hope the agenda is focused on the right problems.