looks like they can talk as long as you have a "W" - however, only in the old modes:
http://reefcentral.com/forums/showpost.php?p=18168399&postcount=2
In order of inception:
MP40 (only speed controllable, identified by a metal box)
MP40w (first to feature the Wireless Wave Driver, often called Gen1's, these are identified by a magnet with a clear plastic coating)
MP40w Gen2 (upgrades included a plastic coated magnet, plastic screw and plastic nut and some firmware updates)
MP40w ES (featuring the EcoSmart driver, these are the latest with an all new driver and box, more water resistant, more modes, better master/slave interfacing, on/off switch.
http://reefcentral.com/forums/showthread.php?t=1944067
I have a pair of MP40W.
I am interested in the new modes that the ES model offers.
Can I upgrade my master driver and have the ES modes on
my MP40W slave?
Thanks
answer:
They will speak with one another in the classic modes but not in the new ES modes. To do that you'll need two ES drivers.
Any pump can be upgraded to an ES model by purchasing an EcoSmart upgrade kit available at our website. Any older pump out there may benefit from a replacement wetside, or at least a wet side rebuild kit, because you never know how the previous owner maintained their pump.
I highly doubt there's any Gen1's out there for sale that haven't already been upgraded so I wouldn't worry too much about that.