I have a Doran and it has been fine. Easy install, support has been awesome. Don't know anyone with a Bartec maybe someone else will chime in. Will say this with the Doran they do recommend metal valve stems.
airspeed - 4/29/2011 3:50 AM I have TST http://www.tsttruck.com/?gclid=CMmDid3FwagCFQTe4AodKwcFqw. I have put about 5000 miles on it and no problems. For the month of April they have a 3 year warranty and free shipping. Not much time left.
We have this same system. It works quite well and has already saved us from one tire disaster when it indicated a slow leak (happned to be a loose valve stem) on top of the North Cascades mountain pass!