seing as it looks like I'll be keeping the TD5 disco a bit longer than I expected, I lashed out on a Bearmach Hawkeye.
pretty neat unit, not locked to single vehicle and you get to have a single access code with it to access one type of vehicle. Can add other vehicle types for more money, or spend bigtime and unlock it for eveything.
So far, all I've done with it is diagnose a crap height sensor and attempt a cunning bodge... basically, since the RH sensor is unreliable, it won't maintain correct height on the RH. So what I did (and tomorrow will tell if this was successful) is to use the test mode to adjust it to approx correct ride height, then tell the vehicle that it has steel springs so that it turns the air sus system off. Initally, it stays inflated to where I left it. quick drive up the road and back and no change.
will see if it's still up in the morning.
Unit doesn't have the capability to calibrate the air sus, unfortunately. Still, can't have everything, and it does do a load of other stuff I've not looked at yet, including letting you look at live data to see what's doing what.
it's actually made by omitec (IIRC), and you get the unlock code from them, took about an hour or two by email.