What he said. I try to rebuild these as I get a chance, but get lazy sometimes. That said, 480 degrees and 30 joules is what I set my M class to and the coils last about a week or so. I vape a custom NET mixture of Cherry/Vanilla Black Cavendish, Vanilla/Caramel Cavendish, a full bodied Cohiba, and a medium bodied Dominican cigar. The juice is pretty dark and sweet (as far as NETs go) and I really don't have tons of issues. After about 2 days, there's certainly gunk on the coils, but it doesn't impact flavor or vapor production until day 8 or so. Order the authentics from Fasttech in bulk (I get three packs of five at a time) and plan ahead for the 2-3 week shipping and these run $2 apiece. I've rebuilt these (both horizontal and vertical) for a fraction of the cost, but the horizontal coils don't perform and better or worse. The vertical coils perform a bit better, but they're a pain to build.
I'd wait a bit, personally. Kanger is about to release the new vertical OCC coils and I'm sure the vertical nickel coils are right around the corner, too. Fasttech should have them in short order right afterward. Just make sure to buy authentic coils from them.