I didn't meter my coil, but 5 turns at 30 gauge is pleasantly warm at 4.2 volts. The biggest drawback I can observe so far is that 30 gauge is stiffer than 32 gauge and a little harder to twist. I stabbed my finger a couple of times twisting it onto my silver NR wire. However, after the joining, wrapping the coil around the wick wasn't difficult.
You definitely need a thick wick to be able to feed
juice to the coil fast enough for a 5 turn coil though. I make my wick 6mm thick, so no problem there for me. However, flavor seems to be a little richer with 32 gauge Kanthal -- maybe because it burns a little hotter? The difference is minor, though. I think next time I'll shoot for a 4 turn coil and see whether that improves the flavor saturation. Because of the temperature difference, I'm also curious to gauge the longevity of the 30 gauge. I typically only get 2 - 3 days out of a 32-gauge coil. We'll see how long the 30 gauge lasts.
I'm not sure whether this will affect battery drain for good or for ill, if at all.
My initial impression is that 30 gauge is a suitable substitute for 32 gauge if you want more
coils while maintaining low resistance. I haven't fully developed my opinion yet, though. But if you can't find 32 gauge, by all means, go for the 30 gauge.
EDIT: I changed my mind. 30 gauge takes too much wattage to heat up. I usually vape on 32 gauge with my Kick set to 8.5 watts. The resistance of 30 gauge is lower, sure, but it doesn't burn as hot. Vaporologist made me a coil with 34 gauge and I could tell a big difference. My 5-turn coil I made yesterday metered at 1.2 ohms, but it still didn't burn as hot as V's 1.8 ohm coil, even at the same voltage. The flavor is much richer, even at lower voltage and power. Better to go fewer
coils with wire that burns hotter than more coils with thicker, slower heating wire.