Preclearance is here to stay, but in no way should we allow:

a) Armed US customs/immigration officers on Canadian soil
b) the removal of the right to withdraw from preclearance quesitoning without penalty (detention, etc)
c) the right to strip-search or even stripsearch a traveller without a Canadian border security officer present.

It should be made very clear to all in the preclearance area that you are allowed to walk away from questioning at any time and leave and that canadian law is in force and trumps any US border agency rule.

I see no reason why any aspect of Canadian law should be abrogated. Nor that the right to walk away without penalty should be removed.