No problems so far with the primer bulb. I came to the idea because I wanted an easy way to prime the carburator after a prolonged standstill (weeks/ months) instead of making the starting motor labour to do exactly the same thing. Starting the car after a short period of time is no problem and has never been.
I understand the concerns about the priming bulb being in the engine compartment and positioned the bulb against the right fender so it is as far from the engine heat as possible. No deterioration of the bulb material (which is not rubber) as to this point, but i will keep an eye on it.