I like using the G5 as an altitude encoder when possible. It only makes sense in that it not only is a digital source, it also reads your altitude at all times in flight. Plus there is no added cost, weight or plumbing for a stand-alone encoder. That being said I had a G5 go haywire with about 20 hours since new and it started running the altitude from below sea level to 30k+ feet and all points in between randomly in a matter of seconds. The bird was departing the LA Basin and So. Cal approach got all in a tizzy with the altitudes being reported. Got the notice in the mail from the FAA ADS-B team and I had to write a letter stating I swapped out the air data computer with a loaner G5 and promised not to ever let it happen again if I could help it, I guess. I have never had a lick of trouble before or since with a G5.