Since we don't have a low resist AE mez spell (no beam of slumber), I decided to test out my level 119 AE mez spell to see how much it was resisted. My target happened to be a dark blue con (level 117). On 10 casts, it was resisted twice. So, if cast on a group of mobs, most of them will probably be mezzed. I think that success rate makes it useful, although I would love a beam of slumber upgrade.
The wave spell you can mez yourself, and it's even more of a risk with the low resist version. I prefer the splash mez, as I can't mez myself with it, and also 1 mob being weird doesn't throw off my intended cast diameter. I usually keep splash, PBAE and single target loaded. What splash doesn't hit, the PBAE will get. I'm also quick to throw a single target banish and mez on a mob that resists. Beam is great, but it's usually not a huge priority to me on level increase expansions, instead getting the upgrade focus AA, some class stuff, etc, so I go a while without it.
