Late Fall, Wine, and a superb combo - the NX300 & 16-50 f3.5-5.6 PZ

IMO, lenses are one thing, and the camera is the other.  The question about taking photos of fast moving kids indoors has been that is constantly being asked on all of the forums.  But it's both a synergistic thing between a camera (that can handle fast AF in lower light scenarios) and a good lens.  Of course, if you have a camera capable of very fast AF, then putting on a slower lens doesn't really become an issue, unless wanting "f2.8 boket scenarios" is what you're looking for.

Heck, I'd love to get the 16-50 S lens right now - but on the NX300 it would look ridiculous and not ergonomically sound, and I just can't afford it right now.  Which camera would you be using the lenses on?

As for the PZ lens, it fits/matches the NX300 beautifully and I've been nothing but impressed with the images the combo is capable of achieving.  I've done indoor scenes (nothing special as far as content is concerned) with this combo and I haven't had an issues so far - but then I'm in my 60's and I don't have any grand-kids running around either.  Heck, I would imagine getting the NX1 with 16-50S combo would be the thing you are looking for - but that would result in your lugging around a DSLR-sized outfit (heavy).

I own somezoom lenses right now (not necessarily in the Samsung brand) that have given me near prime lens results (i.e. Leica Vario zooms for my four thirds cameras).

The only two lens I have right now in the Samsung line are the 18-55 III kit lens and this 16-50 PZ lens.  As for lens recommendations, I'm afraid I'm more of a zoom person.  I rarely use primes with the exception of the Panny 20 MM f1.7 which I keep on the Olympus E-P3, where the combo is absolutely superb!

But I noticed that your requirement for a smaller-sized zoom lens implies that you are in fact leaning towards getting the PZ version of the 16-50.

I've only recently have come to Samsung (a year ago), and I'm a strong user of both Four Thirds, Micro Four Thirds, and the Fuji X line of cameras (even have a Canon EOS M).  But the more I use Samsung cameras (currently only have the NX300 and the EX2F), the more I'm drawn to the way they handle colors.  So eventually the NX1 will be in that collection (meaning I'll have to sell off some stuff - actually, lots of stuff).

I hope that somebody else - with more experience with various Samsung prime lenses can chime in and help you here.  Perhaps you should start a whole new thread on that subject as it will generate the most attention (and opinions).