The MVP can handle an RDA, but you'll also need to target 1-2 ohms (the 20W won't fire anything below 1 ohm). That being said, I'm pretty happy at 1.2 ohms on the 20W - but if you want room to grow, you might look for a mod that will fire something a little lower. (dual coil setups, for example, are pretty much always sub ohm - which isn't where you'd start building, but eventually you might like the flexibility to go a little lower than 1.0!).
I actually ran a SMOKTech RDA on an eGo ages ago, as my first dripping experience. It worked actually surprisingly well! You can always mess around with building coils, just know that you'll get better performance with your next mod. (and make sure to check your resistance before screwing it onto the eGo! if you try to fire something sub-ohm on an eGo it will, in the best case, shut itself off completely until it's plugged into a power outlet... learned that lesson the hard way!)