I've only used the slotted and do notice the darkening you speak of. I tried the dry burn as the previous poster mentioned but then I found myself with another 3-4 day break in. That may indicate my wire isn't wrapped tight enough. I'm using nichrome 32g with a 4/5 wrap at 1.9 ohms. I run it at 4.1 volts. I'd like to go higher but notice when I do I begin to get hot spots which I suspect indicates also that my wire is not tight enough.
In general I think you will find the thicker gauge wires will give you better results. The wick will warm up quicker and you will get better coverage yielding more vapor and keeping the resistance down. 32g is just too thin in my opinion. I use 28g now and it gives a really nice vape. I would also try and get your resistance down a bit. Try a 1.3ohm build with some 30g perhaps and see what you think. As you have also mentioned, you need to get the coils tight on the wick. Any air gaps in there will give you harsh vapor.

