While it may be true that electrolytic caps may still function after 30-60 years it does not mean that they will function as new. Check this for a discussion of why.
http://powerelectronics.com/mag/power_internal_construction_boosts/
Since Naim recommends replacing their caps after a period of time either:
A. some parameter of the caps changes over time that will degrade the sound of the unit or
B. Naim is running a big scam to generate extra revenue.
If you go to Naim's website they have a very active user's forum where you can find tons of info.
If you are going to sell I doubt you would recover the cost of recapping.
http://powerelectronics.com/mag/power_internal_construction_boosts/
Since Naim recommends replacing their caps after a period of time either:
A. some parameter of the caps changes over time that will degrade the sound of the unit or
B. Naim is running a big scam to generate extra revenue.
If you go to Naim's website they have a very active user's forum where you can find tons of info.
If you are going to sell I doubt you would recover the cost of recapping.