Ratman can answer you, but I will too.

Okay? Ha. I never thought I needed VV....and when I got into RBAs I REALLY assumed that I didn't need variable voltage because (logically) I figured I could just build the coil to any ohm I wanted, and the 3.7 (actually about 4.1 watts) would be just fine. THEN I got a VV Grand.....now I can't live without it. Period. If I could only own one REO (in some alternate universe....never happen to me in THIS life!!!) I'd have the VV Grand. It's my 99% of the time go-to apv. Couldn't live without it.
Just thought I'd drop that opinion in here....take it for what it's worth.