What's up with Persuade?

Another post from the ranting "What's up with...?" series that focuses on vocabulary words we can't quite get a straight answer about.Look in the dictionary for "persuade" and you basically end up with:

• shuōfú 说服
• quàn 劝

Now, let's ignore (for this whole post) the fact that these words often mean "try to persuade" and talk about the following two statements that native speakers around me insist on:

1. "We don't use shuōfú 说服. That's more of a formal / written form."

They claim to prefer quàn 劝 in spoken Chinese. It would be nice if the dictionaries mentioned that, but I'm actually not even convinced it's true. I'd like to hear what other people from other parts of the country (I'm in Guangzhou) have to say on this matter (please leave comments here).

2. "And besides, 说服 is really pronounced 'shuìfú'. So 'shuōfú' is a mistake.

MDBG gives "shuìfú" as the Taiwan pronunciation, but I've never heard anyone down here say anything BUT "shuìfú" (and my friend Tommy has never heard anything BUT "shuōfú"). Also, a student told me the other day that during high school, in preparation for the gāokǎo 高考 (which includes a pinyin section to test students' Mandarin--I'd love to get a hold of some online materials for that by the way if anyone knows of any), they were told to give the correct pinyin for 说服 and if they put "shuōfú" it was marked wrong.Now, I know that informants are flawed and can be prone to shooting from the hip, selling their own opinions as universal laws, and are always influenced by their own fāngyán 方言 (this is Guangzhou, after all). But it's not only one person who's saying these things.Also that gaokao story had a sort of ring of truth to it. Why would the character 说 be included on a test if it was meant to be pronounced the same way it always is ("shuō")? At the same time, none of my dictionaries give "shuìfú". So, what are we to think? Any ideas are welcome.