Communication is 2 way affair.
If you use good english when listener cannot (or not used to) use good english, the communication will not be as smooth.
That is why PCK is more popular than other series in singapore.
That is my many unkers scratch head when some guy speak in parliament, cos his engrish too powderful.
So if you are in restaurant in europe you say the right pronunciation.
If you order the same thing in singapore you pronounce just like what they majority of the population pronounce it, else you may not get what you want which is worse.
Anyway...
you say po-tay-toh, I say poh-tah-toe...