No. I get a little nervous giving out my Visa details.
Yes you'll get more buyers for the higher priced items. there are a lot of impulse buys from people who have some money in their pocket but not enough to meet the selling price. I would accept it, ask the credit card issuer about how to protect against fraud. Any number of fraudulent payments are possible according to what I've heard about ebay etc. Probably the best way is to sell to people who have a good reputation that you can check on i.e. references etc.
Unless I am mistaken, MasterCard offers some kind of protection for buyers who purchase via Internet. Not that it means a great deal, but, somehow, I feel that someone who has taken the steps required to accept credit cards is less likely to ship a box full of bricks or malfunctioning speakers or whatever. I think its a plus, yes, even more so when I think of the hassles of using PayPal.