Would agree BTC or Bitcoin has no real diffrence what way you say it. the value is the main thing 
True BTC or Bitcoin really don't have difference since the first one is the ticker of the latter one, what being discussed here is the right term to use in case there is more than one (1) Bitcoin. The author want to know which one to use Bitcoin or Bitcoins.Personally i used to say/write 10 bitcoins but this is my last concert, i actually have a problem with writing 10 satoshi or 10 satoshis!
hmm i don't think you have problem writing satoshi with s at the end, coz you just wrote it . See my proof above 
(just kidding)Is it? Xe.com reel off prices in 'XBT'. To quote them,
Quote
There is no official ISO currency code for Bitcoins, although XBT is commonly used.