Charming is rough - the biggest indicator is your level. I've noticed almost no difference with CHA, playing naked or geared, that would warrrant me dropping massive amounts of INT for it. If the mob is a white con, or 1-2 levels below you, you're not holding it long, regardless. 200 CHA will not change that. I hold low DB mobs for 3-5 minutes without issues with 137 CHA. You will never need to hold a charm solo that long. One of these days, I'll write a decent charming guide, but from 12 on that should be your soloing tool - dotting just takes too long with Choke. Or a good group, as always.