You can find all information about the v1.2 SMD here:
[
reprap.org]
Quickly reading over it I saw:
1. It has ethernet connectors for the opto endswitches, which are backwards compatible with the 1.1 version. You can solder in a pin strip or any other connector. No problem.
2. It has an IDC connector instead of the old directly soldered wires. The pin functions are the same as with the old version, though. No Problem.
3. The normal jumper for the stepping mode has been replaced with a solder jumper. No problem here.
Please anyone correct me if I am wrong
I'd use the new version and the new connectors if I hadn't built mine yet.