I'm
vaping both at the same time with the same
juice, the .8 on a provari, the .5 on a Sigelie. Both at max watts. The .5 has seen too many mls and needs a clean-up, but is still performing great. Its instant-on, nice and smooth, but has a bit more edginess (in a good way) on the vape than the .8. The .8 is slooooow. But once it gets going it is very smooth. Almost too smooth, no throat hit except for the 6mgs of nic in the
juice. It almost seems like its asking for more power. Both produce the same quantity of vapor. Large clouds! They are both great.
I find myself using the .5mm regularly and then I reach over for the .8mm and then go back to .5mm. More so because the .8mm is on a Provari mini and that 700mAh battery last only for about 10 minutes of vape time at the amp draw level.
If I had a mechanical and could push 20 watts into the .8mm, I would use it 100% of the time. But since I dont, the .5mm is the better balance.
Sorry, long response to your question and then some, but until you asked, I really did not think about the comparison.
Short Answer:The .5mm hits great!
Bottom line: .5mm for VV/VW devices, .8mm for Mechanical devices. Sorta the same conclusion as round wire 30g vs 28g.