I am using the Maestro 1035 http://www.mouser.com/ProductDetail/Maestro-Wireless-Solutions/A1035-H/?qs=sGAEpiMZZMsa9w4dmI1JYEv5hDt7Ew5Y and the 2035 http://www.mouser.com/ProductDetail/Maestro-Wireless-Solutions/A2035-H/?qs=sGAEpiMZZMsozux2%2FwCmWzf0tcKPfaAL, as I mentioned in an earlier post some GPS units do not support PPS output and that may be why your datasheet does not mention. I have yo admit that the PPS signal is probably useless to all but a very small percentage of the users.
I have some 1035's in hand otherwise I would only have the 2035's as they have better performance a few bucks cheaper. For either of these modules a breakout board is required and I could not find one on the 'net so I designed one myself, but the design is not ready for primetime right now.
The +/- 50ns is probably correct given 4 or more sats, and you have to ask yourself is that good enough and I am pretty sure the clock speeds on the ATMEL 8-bits MCUs is such that the MCU timing will add more uncertainty than the PPS signal. The GPS units process the data from the sats in pretty much the same way so the PPS signal from one GPS is good as any. When I contacted Maestro with a technical questions re: the PPS Larry responded to me that they did not recommend using that signal for timing and I was a little confused. I emailed Larry back and asked him why and he stated the PPS signal was not exact and it could 50 ns off. I knew for my apps that level of uncertainty was fine, but everyone has to ask themselves the same question but I imagine that is fine for most users here also.
wade