I asked some questions on the ATC forum when you posted the first alert on Mode S, and got the impression that there were sufficient problems and sufficient unknowns that the experts would be unlikely to impose mode S on GA without more thought.
If my impressions are wrong perhaps I should panic at the cost implications.
However, the knowledgeable people on the ATC forum threw up so much technical detail that I found it difficult to formulate what might be considered to be a balanced objection.
To object on the basis of cost would be valid, to object on the basis that the cost is not justified is more difficult without really understanding the problems it would cause if GA was exempted.
To object on the basis that there should be cheaper technical solutions to the problems is voicing a suspicion, but without a solid basis of knowledge.
Can you help with a precis of the pro's and cons?