As Micky found out, the original advance unit wears, and as yours will be coming up for 40 years old, it will probably be worn too.
The Microdigital, or the Micropower if you fancy a new twin outlet coil, is cheaper than the OEM advance unit, and is a fit and forget unit - I havent touched the digital I fitted to my /75 twelve years ago, so it has probably been cheaper than replacing points and condenser .
And no more burnt wrists setting the timing.
If your existing system is working like new, and your riding style is such that you keep the motor spinning over 3000 revs you wont notice much , if any, improvement in the way the bike runs - even the very expensive crank mount systems are undetectable when switchable back to back with a good points system.
But if your old system is getting a bit tired you will notice a difference.
Some also claim that the improved curve improves slow running, to the extent that 1800 revs in top is possible, but I for one am never going to find out if that is true, as I keep mine spinning a lot faster than that.