More controllers better than more gadgetry in a/c
In my opinion, for what its worth, the LARS and ATC of the larger airports e.g. class D do an excellent job. Unfortunately, due to their limited resources they cannot always give a zone transit or RIS and sometimes only a limited FIS.
Many times when I have received a RIS or just a FIS this has helped me see aircraft in the vicinity that would have been hard to see otherwise e.g helicopters (faster moving a/c are sometimes easier to spot than slower helicopters or microlights, which may remain closer to you for longer).
I think a few more controllers available to assist GA light aircraft would be a better use of resources than all a/c having mode S or TCAS. To the guys and girls at LARS and at various airports like Luton and Farnborough keep up the good service.