The M3 and R4 are exactly the same, both work with the EZ-V 3-in-1.
As the name implies, the 3-in-1 was BUILT for the EZ-V, so to answer your question, yes it does work with it.
As the M3 and R4 are the same thing, your choice lies between either of those, or the EZ-V. Since the Homebrew loader thing for the 3-in-1 gives pretty much full compatibility, and since the R4 & M3 are less hassle than the EZ-V (i.e. no updating of savelists etc) I would go with them.
The R4 gets updates about a day or two earlier than the M3 so its probably the one to go for, however both cards are exactly the same and the M3 always gets the update a day or two afterward.
A great place to purchase these cards is www.dealextreme.com who have good prices on both the M3 and the R4, as well as the EZ-V and the 3-in-1 expansion.
Hope that helped!