I went to an event (Book of Mormon @ Princess Theatre) on Friday night that I sourced my ticket thru viagogo. Was easy, worked perfectly, happy days.
The only thing I will say is there was an unexpected booking & handling fee that I didn't know about until I got to the checkout stage. So what was listed as a $250 ticket ended up actually costing me $317. But I decided it was worth it anyway. But yes, expect $60-70 on top of the listed ticket price which I assume is viagogo's cold hard profits.