I think creating names for 0.001, 0.00001, etc. is silly.
Just use two different units BTC and something like satoshi/bitcoinunits/bitcreds/credits representing 0.00000001 BTC.
The problem with milli/micro/nano is that when you get a bitcoin amount like 0.00245678, what random btc name do you use..?

Also it's a LOT easier to tell the size of something when it's larger because of commas and no leading zeros:
eg 34,400 BCU vs 0.00034400 BTC