PMP100 - Will a 5700SMG P11 SM connect to a 5700AP P9 AP?

I opened up a pack of 5700SM P11s we purchased recently and saw the part number was slightly different than before - it now says "5700SMG" instead of just "5700SM". On the main configuration page it also says "P11 C25E" where it usually simply says "P9" "P10" or "P11"; I can't find any information about what "C25E" signifies. In the Radio section it also shows a different way to configure "Transmit Power"; it shows  "dBm ( Range: -3 — +23 dBm )" instead of the usual "Normal"/"Low". I included images below.

Will these SMs be compatable with our current PMP100 APs which are mostly run of the mill P9s?

The hardware is compatible (i.e. anything P9 or later will connect to each other).

There are, however, some software incompatibilities that may arise.  What version software is on the P9 radio?

Regarding the C25E, that refers to the FPGA chipset that was used on P11... 

Thanks for your reply Matt. The P9 AP is on 13.4 with Canopyboot 4.0, while the P11 SM shipped with 13.4.1

There should be no problems connecting a 13.4.1 SM to a 13.4 AP.

I would agree.  You should be able to do this.  If you have issues, please post here, and we will try to help.