Anyway, i have kept tire pressure consistent, have reset tilt on each ride (and have even taken to doing the tilt while sitting on the bike), i have done a new profile (10 coast downs and a 14 mile out and back ride),have not changed the mount position, and have acclimatized the unit each ride. The desktop software indicates properly on loop rides, meaning imho at least, that the vertical gain and vertical loss should be within a few feet of each other...and they are. The altitude profile does not show a constantly increasing profile either (like in the flat tire scenario), but I dont ride on any long stretches of flat road that would truly show such a situation.
Thanks.