I always offset 1R while en-route in Brazil nowadays.
Is it not a bit simplistic to ask about TCAS serviceability though? Surely it is as much as question of mandating the use of Mode C with altitude (as opposed to switching off the txpdr) so that TCAS equipped aircraft will at least be warned of other aircraft in the vicinity, even if not afforded full Collision Avoidance for which both need serviceable mode S working?
Personally I would obviously prefer everyone to have full mode S 100% of the time, but you have to make allowances for defects away from base, and for me so long as the aircraft has serviceable mode C that should suffice.