I've got a reel of 910 - never had any joy with it. taulman say that it really should be used in a heated print volume. Also 910 has pretty obvious shrinkage factor.
That's the good thing about 645 - it will work well unenclosed and doesn't shrink enough to worry about.

Hand down the best nylon on the planet for printing on normal/cheap printers is Mymat nylon. Expensive, but zero shrinkage great adhesion and just hassle free printing. You still get some stringing - but it's nylon, expect stringing.
http://www.mymatsolutions.com/products/

Avoid anything that just says: nylon and is cheap.
It'll usually be a total nightmare to print with.