Interesting thoughts. I'm just saving up for the Zaon PCAS system and will upgrade my Garmin 296 for a 496 so I can see traffic on the screen. I know it will only show those squawking mode C but every bit of help is useful in my opinion.
Insterestingly at a recent CAA safety evening, I questioned the speaker (CAA chap - well known bloke in General Aviation this month) who was going on about a new Exeter Class D zone (and others). He said that if any VFR pilot gets a refusal to enter a zone we should MOR (report) it to the CAA. He said that CAS should not be an exclusion to VFR traffic (all well and good and all with a pair of rose tinted spectacles IMO).