I'd like to hear their explanation of how new air bags can be "too much" for an old compressor. I would think new air bags would be better for it as they wouldn't have any leaks and wouldn't require the compressor to run as long or as often.

Generally the compressor starts to sound like an old diesel truck for quite a while before they actually go bad. If it's not noisy or demonstrating some other abnormality, I agree with Byron...leave it alone.