I don't think it ever has been soloed, and I think you either need quite insane dps in phase 2, or a healer, to move that channeling beam away from the guy (cant remember his name, been ages since I did that fight)
As for the plague when having 2 people, if you want to be safe, bring a
Purification Potion. Between that and AMS, can't die from it really.
That said you ideally avoid the plague totally by having your friend run away from any adds and letting it run out. As the plague kills off all the Shambers you want alive for vengeance.
Edit: Enlighten me what the use of hard cap expertise is, because I can't see the use of it over more haste/crit.