How do you find the MRX unit? The owner of the plane I am buying is throwing in a XRX unit...
The same as lenthamen. Mine is about 4 years old, though it was overhauled due to a defect a few years ago, but recently it has been showing what I consider to be ghost traffic .5nm away and 100ft below - which I know not be true. It has made me aware of some things I haven't seen, but its certainly not trustworthy enough to rely on without looking out or getting a traffic service. I did consider the XRX, but if its as reliable as the MRX, I wont waste my money. Plus it seems the only service centre is in the US, so even an inspection of repair costs a fair few dollars. Better than nothing though....
Nowadays 90% of my flying is IFR on Airways
I would not spend any money at all for that. You will be lucky, on say a 900nm flight, to get 1 or 2 targets showing even on a "proper" active TAS system, configured for say +3000ft to -3000ft and with a 10-15nm range.
Obviously somebody could be busting CAS but the odds are vanishingly small at any significant altitude. I would bet 99% of CAS busts take place at a very low level, say 1000-2000ft, which is the typical GA enroute altitude and they get lost. And even those CAS busts are very rare, in the context of an IFR GA pilot doing say 100hrs/year. The UK suffers badly from CAS busts but even the UK gets less than (of the order of) 1000 busts a year so the chance of getting one on your flight is close to nil.
That proon thread is perhaps a reminder of what you get if you moderate a forum for advertising revenue.
I have flown with the XRX and it did generate a lot of false alarms. It was a bit like a radar detector for a car. It will pick up the speed cameras but it picks up so much else... I wonder if the company has some patents, because the state of that technology is quite poor.
I would not spend any money at all for that. You will be lucky, on say a 900nm flight, to get 1 or 2 targets showing even on a "proper" active TAS system, configured for say +3000ft to -3000ft and with a 10-15nm range.
I disagree, I get lots of traffic showing at airways levels.
FL250+ ?
Getting really close so you have to suddenly avoid them?
I just read the PPRUne thread....after your post Peter it all went markedly downhill and turned into a p****ing contest! But I did glean that there are apparently some (many?) users who experience ghosting problems....still I won't look a gift horse in the mouth!
FL250+ ? Getting really close so you have to suddenly avoid them?
Of course not. But you often say you see no traffic. I am just pointing out that I see lots of them on the TCAS at altitude.
I see lots of traffic, too with my PowerFLARM, even in the UK. 
In VMC, I am able to spot about 80% of that traffic if I'm trying hard.
Rather than argue about grammar or semantics, the point I was hoping to make is that the case for spending money on something like this depends on your exposure to a possible mid-air.
A GA pilot flying predominantly or totally in CAS has no case for it, unless the circumstances are very unusual (e.g. the radar controller likes to sleep a lot of the time).
If that was not the case, there would be many CAT-GA midairs.
A GA pilot flying in a busy GA environment, at a level where most GA flies, does have a very good case for it, but if flying at a low level, say 1000-2000ft, he needs to be aware there are going to be many nontransponding targets.
I don't know whether the UK is unusual in Europe in the non-TXP traffic density versus altitude.
FLARM usage is clearly country dependent. In the UK, almost no powered GA uses it.
ADS-B is currently irrelevant, although somebody choosing a Mode S transponder might want to choose it for upgradeability.
I find my TAS605 system very effective and it has avoided several very close situations already, but it was very expensive, at very low levels (say below 2000ft) it shows perhaps less than 50% of traffic (as would also be the case for the ZAON products, PowerFLARM, etc), and in IFR/CAS flight it shows very little in the FL100-200 range (due to generous Eurocontrol routing separation in the terminal areas, and ATC traffic spacing) but there one is not looking for midairs anyway.
FLARM usage is clearly country dependent. In the UK, almost no powered GA uses it.
It does not matter what percentage of powered GA use FLARM. It is only relevant what percentage of gliders use FLARM. In Germany, Austria and Switzerland that number is close to 100%. FLARM only uses its own protocol to detect gliders, the signal is too weak for two motored aircraft on opposite course. To detect motored GA, it triangulates the Mode C/S transponder signal.
ADS-B is currently irrelevant, although somebody choosing a Mode S transponder might want to choose it for upgradeability.
Instead of mandating Mode S, 406MHz ELTs or 8.33kHz VHF, they should mandate ADS-B out. Then everybody could get a bulletproof TAS for a few hundred Euros and the need for 13k€+ active TAS systems would go away.
Instead of mandating Mode S, 406MHz ELTs or 8.33kHz VHF, they should mandate ADS-B out
I believe there is a 3-letter place in the known universe where this is the case, or will be soon, but one is not allowed to mention it in Europe
However, for Europe, I can see the same wars being fought over this as were fought over Mode S, with the result that most light GA will be exempt, so it will be almost useless for "TCAS" purposes.
