I don't know why anyone would argue against traffic info in the cockpit. The world would be a safer place if everyone had a transponder / some method of broadcasting their position, and then those that wanted to could have a system to display conflicting traffic?
The TIS systems I have used in the USA are NOT TCAS but they have brought to my attention numerous targets which I wouldn't have otherwise seen - as displayed here. If nothing else as long as your altitude is different, a collision won't occur. You can also see altitude trends so if they are climbing or descending.....
I believe FLARM costs aout £500. If everyone in the UK or indeed Euroland decided to fit FLARM the cost would probably drop by half. They already offer discounts of 20% I think to 15 units or more, which I'm sure could be negotiable if someone decided to order several hundred or thousand.....
