Now you see, if I hadn't posted such a comment I would never have got such a detailed response
Only ATPL level thoery here. I'm keen to know what I am wrong about though. An RA in controlled airspace must be reported, so they are taken pretty seriously. If you turn RA off, then you have a potentially more complex situation perhaps? Its fine if you are the only bod for miles using TCAS at 2500' in and around Farnborough (possibly a bad example because of the number gliders), but if everybody else (the original point) was flying about in Class G with TCAS in TA mode only, how exactly would the multitude of warnings be resolved? Just more possibility for somebody to misinterpret the screen and climb when they should be descending. Also, you said it, "commercial", you are properly trained and well practiced in its use. If we all had TCAS then would that really be the case?
I really understand if you are fast traffic, the sitaution is different, but the point IO540 was making is that we should all have TCAS, that is my point of contention.
Although the visual lookout is inefficient, I'm not sure it is neither ultimately ineffective nor inappropriate for VFR. Also, the lookout is proactive activity. I personally think that technology could lead to a more reative approach to flying. I can't see how that can be a good thing.