Yeah Philpass is right.
The engines are pretty much bullet proof with minimal maintenance.
Quite a few have problems with electric starting. This can be one of 2 problems.
The starter clutch is definitely a weak point. It is the same starter as used on many other models from 400’s to the legendary 900’s. As the twin has a higher compression than the other models it appears to have reached it’s design limit and they can easily fail.
With the starter motor being situated at the front of the engine it gets battered by the elements of our wonderful British weather. This can cause corrosion and deterioration of the starter cable and connection thus reducing the power it can handle. Couple this with the effort required to turn the engine they can need to be refurbished to keep them on top of their performance.
Responses like you got from your MOT guy are typical of what we receive almost everywhere we go but that is their ignorance. Anyone who has a twin will tell you how well they run when they are set up right. It is the time and effort sometimes needed to get it there that puts people off. They give in before they get it right.