Even though I have VW available on the Vamo, I find I'm able to fine tune better using voltage rather than wattage. If the Vamo were able to adjust in .1 increments on the wattage side, it would be much, much better. So yeah, I tend to stay on the voltage side of the device because I'm able to find that sweet spot easier.
Have another think, because it's not that bad. The volts function incorporates the inverse square law, so it HAS to be fine tuned in 0.1V increments.
Your voltage range is 3V to 6V in 0.1V increments. That is 31 discreet settings
your power range is 3W to 15W in 0.5W increments. That is 25 discreet settings.
Both of these have the same range on normal resistance or high resistance coils. There's really not that much difference in one step between the two. There's some cheaper devices out there that do VW but do it 1W steps, and start at a fairly high 6W. I'd advise people to keep this in mind when buying VW on the cheaper end of the scale, but there's really very little problem with 0.5W steps on a device. 0.1W steps would just be ridiculous (because of the inverse square factor - I don't really want 121 discreet settings.
For example on a 2 ohm coil, 6.5 Watts is 3.6 volts
6 watts on the same coil is 3.464.
If you equate that to VV settings of 3.6V and 3.5V, the error factor is 0.036V, not enough to matter - it's unlikely you could tell the difference. How long you hold the button down will have a far greater impact on how hot the coils gets.