I agree with what you say there Wolf - this isn't about the sort of quality recording we are used to as musician - but more an adudio notebook where we can record the band, li-fi, just to understand the basics in rehearsal (what it sound like over there in the bar) so so glaring mix errors can be fixed, recording a student so they can hear and critque themselves, create a little 'exam' like pressure on them and generally just have something around that we can use to play back an idea, whatever. So cheap and easy was the top of the list. You're absolutely right that there are some great stereo, hand-held recording devices out there - but generally I found these to cost 10x more.
I'll keep everyone in the loop on how I've used the Sony 133. So far I've recorded students playing -good results so long as the volume was down - clipped otherwise. Would be easy enouth to record a whole lesson - so long as the volume was kept at a conversational level - this is when you realise you want compression and some EQ and level checking. With this device you don't have anything but simple on/off recording.
More to follow. I'll post some recordings soon.