possible, i have WAAS/EGNOS switched off in my Oregon300 after a strange behavior on a hiking trip. Here in germany i have not often a EGNOS lock. The track logging was ok, but after a walk of approx. 5km the track becomes erratic and begins to drift away. After a error of 50m i was wondering whats going on. I looked to the sat page and there was an WAAS/EGNOS lock (the D under the satelitte bars). I immediately switched off EGNOS and the track was stable again, also the drift was corrected after a short time of walking (power-cycle the device was not required).
Maybe the people who wrote that a power-cycle was required to correct the drift has no WAAS/EGNOS lock after restart?! Now my Oregon runs without WAAS/EGNOS and the tracklogging is ok. It is not perfect, but it is also not so bad as it was descibed in this forum.