People cna say what they want about the NS10's, but many hits have been done on them. NS10s are actually very easy to mix on. I do not use them very often, but with a good amp and a decent room, they are really not all that bad. One thing I have noticed is that they work a little better if you push them a bit. They certainly do not have that pristine natural and open sound that better monitors have, but there is something about them that makes them work easily for me.
Just recently I was in LA and did a live mix for a national TV broadcast. The broadcast room had a pair of NS10's and a set on Genelec (1031's?) and subs to go with them on switches. I found it was much easier to do what I needed to do on the NS10's than the Genelecs. For whatever the reason, it went well. Even the house guys told me how nice the mix sounded that night.