The remote sensor unit was a joke. Loads of them were reading wildly off on the OAT. Aspen's fix was quite suprising: a software update
Not had a problem with my Aspen so far but I agree, the OAT sensor in the remote sensor unit is a joke. On most aircraft, the sensor unit will be placed on top of the fuselage which exposes the sensor unit to direct sunlight most of the time (at least when IFR). I found the OAT to overread by at least 5°C.
Recently, Aspen have released a new analog converter unit (ACU2) which allows an external OAT probe to be connected in lieu of the integrated one. I have just installed such a probe and about to have it hooked up.
Other than that, nothing negative I could say about the product. They have just announced a warranty extension -- $700 for two more years.
Regarding the Avidyne -- would have been a great product 5 years ago and really increased competition. Now the not yet released Avidyne already looks outdated compared to the Garmin GTN series.