As for the appropriate wattage I asked a buddy about it last night, and he gave mostly the same answer as some people have answered on here. There are lots of variables which pretty much have to do with what you put on your mod. Some toppers just aren't built for higher wattage, like tanks which can take a while to juice up the wick and are prone to drying out too quickly if used at high power. If we're talking about a dripper, the chamber size and airflow have a lot to do with it. But either way your build has to be juuust so. If you don't wick the coil right, you may get hotspots where the cotton (if that's what you're using) dries out too quickly and burns.
With mechanical mods, the circuit is hooked directly to the battery so you're dealing with unregulated current; if you're subohming that means you can easily pass 150watts or more. As far as I know, only rdas with work with such high power, and again, your build has to be just right to get a nice even vape.
I've been borrowing a friend's dna30 clone and using a magma rda with a dual coil build. Since it's a regulated mod, the ohmage doesn't matter when calculating wattage as they do on mech mods, so long as the build is within operating parameters (something like 0.4-3.0 ohms if i'm not mistaken). That isn't to say though that the build doesn't affect the flavor, it definitely does. With the dual coil build i've got on it now, I find the flavor of the juices i'm using really starts to come nicely between 16-20watts. But when I rebuild the coil, that may change; so it really has a lot to do with personal preference and tweaking everything around until you find the way that you like it.
As for devices that are both vv and vw, they all seem to be either too expensive, or have too low a range for the rdas that i plan on using. So I'm probably going to go with one of the vw devices I already mentioned. That way I can put on a tank and bring the wattage down, but still have the option to do some higher wattage dripping
