I'm trying to see if I need a VV or VW unit.
Are you trying to decide if you need either ?? Or trying to decide between the two ??
For me the answer is yes to either. As far as between the two it doesn't matter to me.
They will both produce the same goal they way I would use them. Which is ....
1) turn down device (either voltage or wattage)
2) put on any atty or carto you like.
3) make sure its juiced up
4) fire it up and take a hit.
5) turn up the device a bit (V or W)
6) repeat (4)
7) repeat (5) until it taste warm and yummy !!
There you go watts or volts it doesn't matter if you don't want it to.
The thinking is that watts = watts on all devices so you could do the Ronco ....
"Set it and forget it" thing with
VW. But the fact is watts don't equal watts with different types of attys and cartos so your always going to be adjusting it anyway. Throw different juice into the mix and theres no way your going to just set across the board and swap different ohm or types of attys/cartos.
Hope my humble opinion helps.
Its nice to understand the numbers game but don't get caught up in it.