I am very curious abou the multiple landing problems. I have had my unit right from the time they came out and am now on V3.6 of the software and have never seen the multiple landings problem. I have used it in everything from my Cessna (which the yoke mount fitted fine allthough I have it on the top of the dash now powered from the "mains") to the Senneca twin. I have however experianced the problem that if you do not pass directly over a waypoint it would not move to the next waypoint in the list and would direct you back. That seems to be cured now in the latest released of the software.
I update my database everymonth on and annual subscription arrangement that gives you 13 for the price of 12.
You do need to use the external antenna on anything that is not a bubble canopy. Even the warrior I had problems with signal reception on the built in one. With the external antenna I have never had a signal problem.
Looking through the logs I have covered 470 hours and 32 thousand nautical miles on my unit in the time I have had it without any problems. I would describe it is extremely good value for money!