Subdivision of BTC is irrelevant to talk about deflation. Talking about this (as the BTC wiki does) is just handwaving and does nothing to address the economics.
I thought one of the problems with deflation was that people used to hoard cash and there was not enough money availale to facilitate normal daily trades. Such thing won't happen with bitcoin.
I think that's not applicable to bitcoin since it's as comfortable to pay with microbitcoins as with bitcoins.