With new water heaters these days I would avoid changing it unless it's neccessary. If you have a heater with a brass hose bib at the bottom draining them tends to be fairly easy. If it's a plastic hose bib there's a chance it won't stop leaking afterwards. You haven't touched it in 11 years now have you, so chances are it's not used to being touched. Important things to look for is corrosion around the nipples coming out of the top of the unit, this can be a bad sign that not everyone knows what looks bad verses what is actually bad.
Not talking about venting, I'm assuming it was all done properly and doesn't look rotten out. The other important thing is the relief valve. Sometimes they don't work if they get real old and never have to open up. If this is the case then opening it up for the first time could cause it to drip forever after. You could end up having to change that or maybe should change it if you are worried about if failing to function in the future. This of course increases a small chance of the tank cracking whenever you drain it down and disassemble and reassemble an old unit. But this is always a chance, and it's better to attempt these tasks when you are prepaired to go the distance if you have to.
Some older heaters go 20 years. It depends on use, craftsmanship, luck, quality of water supply.... If you ask me about new heaters, I'd say your older ones are more reliable than the current generation of products available to you. Go B&W if you do and stay away from American water heaters no matter what. I'm told the current GE water heaters found in ********* are actually American heaters so you need to get to know what their burner assembly looks like so you know what to avoid. A telltale sign is on the bottom of the heater. If it's on legs and has a rectangular area underneath it with a microscreen - it's an American WH and should be avoided at all costs.