Are mixers really useful for large volumes?
This small amount of Bitcoins would be easy to mix. From BitMixer FAQ:
We have a large Bitcoin reserve in our mixer (currently 2100.27 BTC), so you do not need to wait for other users to send coins to be mixed. Your coin mixing will be processed instantly as soon as we have received your funds. To prevent advanced time-based analysis of your blockchain transactions, you may set a time delay for every forward address to receive the BTC. We will then send your coins according to the time delays you have specified.