Other than in catalogs, I've not seen the Nova Midi. It looks like a workable chuck, although the main disadvantage I see is that it uses "tommy bars" to tighten the chuck, not a "key". Here's a pic from the Nova website showing how the tommy bars work:
You push (or pull) the two bars in opposite directions to tighten or loosen the jaws. I've not used a chuck with tommy bars, but I've read there are occasions where you need three hands to tighten them
and hold the turned piece in place. A keyed chuck, on the other hand, uses a t-handled wrench, like this:
I know there are turners who get along just fine with the tommy bars, but I thing anyone who has used both types of chucks tends to prefer the keyed chucks instead.
Another advantage to the G3 is that it uses a replacable threaded insert to attach to your lathe spindle. Because of this, when you upgrade to a
larger lathe, you only need to purchase a new insert, and you can use the G3. That's exactly what I did...I started with a 3/4" 16tpi thread for my little Wilton mini lathe, then got the 1" 8tpi insert when I got the bigger Sears lathe. Down the road, when I buy the next lathe, I'll upgrade the insert again. Three lathes, one chuck. The Nova Midi chuck, on the other hand, has the threads built in, so it's not upgradable.
So, although the G3 is $30 more now, it'll likely save you money in the future.