[jim stamos]"ive read alot shoot in this instead of 1080.
will i notice any difference in pic quality and how much time will i get on 16gb sxs"
Right the opposite.
Every HQ/SQ option (p24/p25/p30/p50/p60/150/160) has the same 35 or 25Mbps, which means that each format allows a different amount of data to encode each frame. Picture quality will differs depending on size and time-base.
A 720p30 picture should look better than a 1080p30.
For the same reason, the time you will get in card will be the same in every case.
You get a 16GB SD card and a 35 or 25Mbps stream to fill it, whatever the format.
If you are finishing in SD, 720 is better option than 1080.