Quit a few other classes can solo it now it seems.
I've personally seen a Brewmaster Lock solo it. Seen a Hunter and a Lock solo it as well.
I've seen a Prot Warrior try to solo it but he couldn't heal back. Not yet heard of a Prot Paladin soloing it.
I first attempted it at around 470+ ilevel. I wipped at around 10%. Most of the times it totally depends on the setup you get.
Vengeful Spirit, Falling Meteor and Fear and any other one is the worst possible situtation. Often times you get feared right into the venegul spirit and it always happens at the worst of times; when your CDs are down and you are low on health from falling meteors.
The simplest ones are the Thunder crush, Sacrabs and Falling Meteor.
You dont get feared that often, just AMS it before the cast is finished. Vengeful spirits are never close when I do get feared because of chilblains and kiting. The only problems I ever had soloing these was opposing faction gankers and the occasional kiting into one of the scouts sneaking in.
The only problem I have with them is that they sometimes reset without any obvious reason. Unless they summon the ghost I just stand still, meteors rarely hit even while standing in one spot and crash is a good source for vengeance.
They're an excellent source of gold and a good way to get the rep (and the gear belonging to them) up for my alts.