I bought a ShaftMasters (SM) 1pc aluminum drive shaft back in Oct' 09 and been running it since in my S13 (weekend mountain carver). It's definitely a quality piece equivalent to the quality you get from the DriveShaft Shop (DSS). You'll get replaceable 1310 series u-joints on the SM driveshafts, but you don't get the re-greaseable zerk fittings that come on the DSS units. That being said, I didn't think regreasable fittings was that necessary; personally I'd just replace the u-joints down the road with 1310 series SPICER ones.
Performance-wise, you will feel and notice first off is a more freely revving motor, especially when applying more than 50% throttle. You won't gain any HP/TQ, but you will feel the rev's climb a tiny bit quicker when laying the hammer down. Also the responsiveness of the power delivery is quite noticeably different. The car feels so much more responsive inbetween on/off throttle applications (e.g. mid-drift or out of corner acceleration).
Comfort-wise, you'll definitely hear the driveline a lot more.. It sounds like a secondary exhaust note that gets louder as the rev's climb. I can hear the diff gears meshing at bit more and I can now hear the backlash in the diff when on and off the throttle. It's very subtle but I can hear everything thanks to the subframe collars and polyurethane subframe bushings. I love performance-oriented sounds so I don't mind at all. If you're concerned about having a smooth and quiet ride, then don't get a 1pc driveshaft. Hence why Nissan didn't put one in there stock.
