Malabo sorry but I don't think you understand the issues. Bristow is not completely stupid (well sometimes, maybe!) and they have only developed this system - at great expense- because of its advantages over TCAS I / TCAD. The fixed wing world long ago recognised the limitations of TCAS I and that is why TCAS II is mandatory on even the smaller commercial aircraft.
The bottom line is that all TCAS / TCAD systems rely on direction finding technology to assess the bearing of the intruding traffic. Because of the high frequencies involved in a transponder, diffraction is a big issue and bearing accuracies are only around +-20 deg, and that is not a fixed error so if you try to assess the track of the intruding traffic you could be in for a bad day. This is why we say its a VFR collision avoidance tool - ie it makes you look for the traffic, then when you see it, avoidance is carried using conventional eyeballs. That's why it doesn't work in IMC.
The lack of bearing accuracy (on TCAS I, II or TCAD) is why TCAS II has to rely on vertical displacments for collision avoidance (vertical position is reported by the intruder's Mode S or Mode C transponder and so should be accurate). But you are wrong to think that means 1000's of feet. A typical TCAS Resolution Advisory will make you climb or descend only 300' or so. Its designed for an IFR environment and will be aware of other traffic above and below you when giving its commands.
Its true that the commanded vertical speed is 1500'/min or so but this is configurable and any helis that can't manage that can be configured accordingly. None of the helicopters I have flown have been limited to below 1500'/min in IMC.
You are also exagerating the g required - flying an RA is not a violent manoeuvre, don't forget you are 30 seconds away from collision at that point and it calls for about 1.2 g up / 0.8g down I think (someone will correct me) which is a long way from negative g. The need to fly the RAs correctly is one of the reasons why TCAS II training is mandatory (in the UK anyway).
I agree that the display of traffic only on the vertical speed indicator is not very good - a cramped display with no other references on it. However this is just for the AS332L, which is a 25 year old aircraft with no fancy moving maps or displays for route waypoints etc. You have to remember that the purpose of this project was to myth-bust the establishment, and Bristow wanted to keep it as simple as possible so that if it didn't work, it would clearly be the fault of TCAS II and not of some other aircraft system.
The plan for all our newer aircraft (EC225, S92, S76C++, EC155 etc) will be to incorporate it on the nav displays.
Yes, I also agree that ADS-B is a good system, certainly much more accurate that TCAS but unfortunately it only works for participating aircraft, and neither does it tell you how to avoid the collision. At the moment the world is full of transponding aircraft that don't have the necessary extended squitter to make ADSB work. So at the moment TCAS detects 99.9% of all aircraft, TCAS II tells you how to avoid them, whereas ADSB would probably detect about 1% and leave you to work out how to avoid them. In the fullness of time that might change but there is a huge hurdle of acceptance to overcome first.
HC