Of all the events hundreds of events we have hosted we have only ever received one complaint from a purchaser. Somebody was apparently using our service to sell "power leveling" sessions for a game the he never received the service after he paid. The ticket price in this case was $20 I believe.
At the same time we have moved over $700,000 in the last 12 months all through PayPal. $20 is a very small percentage so I don't really see events as a high risk. Of course, EventBrite is much larger and they probably attract more scammers.
We exclusively use PayPal as our payment processor and have yet to run into them closing down somebody's account. Our main trouble with PayPal lies in their terrible interface and people being able to override the pingback url.