You can pick exactly what seat you want, get terrific deals (I've always been at or below face value), and as mentioned by Kootenayguy9 the customer service is solid.
I just don't know how Ticketmaster stays in business. It feels like StubHub is world's largest best kept secret.
As for when to buy....tickets definitely get cheaper towards the event time, and you can always find a few seats right in the section you want. Waiting is a good strategy. That said, I bought Yankee and Red Sox tickets months in advance and still paid below face.
tldr; buy now and get a good deal. Buy closer to the event and get a great deal. Either way you win.
Edit: I've only ever bought sporting event tickets - just assuming the same experience applies to concerts.
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