Hey
Bats a single NS10 would be pretty demanding! God they are horrible but good for checking mixes on I do agree. They have a poor bass response and very upper highs so in same ways NS10's do resemble a small mono speaker. By the way these new Yamaha's with the white cones e.g. HS7's do not sound like NS10's either. They are seriously full range in comparison. Although they do tend to push the mids and upper mids a little which is not a bad mix check in fact. The HS7's don't go down that far either so they are good like that too.
To
Leadfoot listen to some of your previous mixes at a lowish volume on the single Auratone and hear the problems in some of your earlier mixes!
I spend quite a bit of time on the small speaker. But I do monitor on the main speakers at 85 dB SPL, 95 dB SPL and 105 dB SPL. (not for long!) It is often quite revealing what you hear up at 105 for example. If the bass is too loud then the room starts to rattle and if there is too much subby stuff in your kick it will rattle your teeth! Also the reverbs really stand out up loud too. Don't get caught setting reverb levels on the small speaker, it lies a bit in that mode.
It is interesting too that on the small speaker a snare level might just jump out a little too much. So you pull it down 1 or 2 dB and get it sitting real nice. But when you go back up on the mains the snare level does not seem to change much at all. In fact it can sound the same as before. But now you have satisfied two speakers at once.
Another thing the mono speaker is good for too is checking the level of sounds you have panned hard L or hard R. In stereo they will always be heard. But on the small speaker you might find they have disappeared a bit. Just nudge them up a db or 2 and suddenly they are there in the mono speaker but not changed much in the mains.