Just had a quick measure of the Aulos 209E and I think the spacings are further apart than your measurements. This is good news! I will struggle a bit for the moment and maybe the hand will stretch (they do, don't they?). And as I said previously, I can upgrade if I decide I like it. I do like the descant,but I am in a group of about 20 and most people seem to have ditched the descant for the other recorders - as a result, there are only two experienced descant players, one of whom does not come regularly and so I have been pitched into playing that top line and sometimes taking over whole responsibility for the melody. This is a bit scary as I have not been playing that long. So I am not sure if I want to be so exposed in the future. We will see.
Misterioso, I did work with the Brian Bonsor book and one or two others (Dolmetsch, I think) and then I plunged in on my own. I play clarinet, so some of the techniques are similar and I knew what sort of effect I wanted. But we had a very good youngish conductor come on Wednesday and he took me out of my comfort zone by insisting on musicality rather than just accurate notes and rhythm. And I am at the stage where if I get these right, I am happy. So that was a bit of a baptism of fire. But as a result, I have been trying to go more for musicality and I am recording myself on the phone. That soon shows up where I need to improve. But it's a brand new world out there, isn't it? Although the clarinet is an orchestral instrument, it hasn't been around that long in comparison with the recorder and so there isn't that much accessible repertoire. I have been astonished at the abundance of the recorder world!