stabout
Sorry, your post read a bit like you were not actually a pilot - had I checked your post history I would have realised that you are a pilot!
Don't dismiss the possibility of getting TCAS just because you fly an old type (for CHC?) - here in Bristow we have a strategy to retrofit TCAS II to all our fleets including the AS332L (well, maybe not the S61!). There might then be pressure for CHC to follow suit.
Anyway, the other point is that Multilat has its limitations like any other system - it only works on transponder returns so anyone not squawking is invisible. And have you considered what you would actually do if you are trundling along at 130kts and ATC advises you that there is a fast jet doing 450kts coming from you 6 o'clock same level.
I want multilat if only because it will cut down the neverending noise on 134.10 with almost every request for climb/descent generating calls from ATC to other helis requesting their position/level, and yes, that in itself improves safety a bit - less stress! And less stress when doing an ARA in the vicinity of other traffic etc.
Every little helps in the battle for safety but IMHO multilat is unlikely to make the difference between me reaching retirement age safely or not, so if its delayed by a year that is a pity but not a disaster.
HC