I don't have a twist, but look at the prices both ways. I stopped ordering kits after my first one, unless there is a good discount. I care more about color, size, getting what I want, NOT getting what I don't want. A $5 discount on a kit that contains $5 worth of attys won't help me, I don't want attys. There is nothing special about kits unless it is what you want AND you are getting a price break.
You asked a question about performance. There are several factors in performance. One is wattage (NOT voltage or resistance alone, but the result of (volts X volts)/resistance
That means with a twist you can adjust for different types of cartos, clearos, tanks, attys, whatever. I've read several different recommendations for watts, some say 5-8 watts is the best, some say 6-8, some say 7-9. It is pretty-well agreed that much over 9 is dangerous, and there is a sticky thread about battery safety that I read, and recommend.
Also, rumor has it (I'm relatively new) that pg carries flavors better and vg makes more vapor, so if you tolerate both, you can figure out what balance is good.
DO NOT buy large bottles of juice until AFTER you have vaped some sampler kids or friends' juice or something and know what you want. Order small to start.
So, as someone who does not know all about this but has spent too much money on oopsies, that is my $0.02
