I meant it in the most positive way possible:

"an aggressively enterprising person; a go-getter."

Hope this helps.

Why hustler instead of hacker, especially in the context of raving about the product?

No particular reason - hustler is just and has always been my preferred compliment for folks doing awesome stuff, whether in code, offline or anywhere else.

I believe he's referring to the more sports-centric definition - people who work hard and fast to get things done.

In basketball, a hustling player is the guy who goes the extra distance, works particularly hard and gets by as much on effort as on skill. The guy who throws himself to the ground after the ball if that's what it takes.

The term seems to have been re-defined in the past year, at least in our community.