I don't think it is a good idea.
BitUsd5 BitUsd6 BitUsd7 BitUsd8 BitUsd9......
Like
Goldcoin10%gold Goldcoin20%gold Goldcoin30%gold Goldcoin40%gold......
May be it will cause competition,and out-of-balance.
But have a try is ok.
Another question:
The Bitusd's largest number of supply100,000,000,000 USD , is fixed or Adjustable?