As I mentioned in another product's review, I put a set of these on my mom's acoustic. She's been lazy to change them and still plays the acoustic semi-regularly, after I played it myself for a long time. The strings still hold and although they're not sounding quite as amazingly, they're not half bad.
When you get a new set of these in, they'll feel really comfortable and they'll sound rich and full. Also, and again, they'll last you a while. I imagine they're great for playing live, as they are quite durable. I would argue that you can keep a set of these up to 6 months sounding quite good, and certainly longer if you're on a budget (or lazy :D ).