For what it is worth I know someone with over 8000 hours on piston Islanders who until not long ago had peltor 8006's at best and still passes his audiogram without problem.
You need quite a lot of hearing damage to fail the audiogram due to long term hearing damage. You will have problems with conversation in normal social settings before then.
But an equally important thing is to be able to hear ATC and passengers clearly, and the best headsets do that best.
If you fly 50hrs a year then you spend at least £5000 a year on flying. Let's say you plan to fly for 20 years. The cost of a decent headset is insignificant.