The Aquila Red Series of strings, for example a low G for ukulele, has raised a lot of interest but as followers of Ukulele Underground Forum will know, some players have experienced problems with them, e.g. strings snapping.
Aquila responded to the feedback very quickly and worked on improving the Red Series, and there have already been favourable responses from folk on the Forum.
I haven't tried the new improved strings yet, but Andrew Kitakis of Hawaii Music Supply has just written a detailed review of the new improved strings and you can read it in full on his blog here.
Andrew also talks about fluorocarbon low Gs, and here's a reminder that Living Water Strings, a brand of excellent quality fluorocarbon strings sold by Ken Middleton, now include sets of strings with low G.