Etherdelta, a successfull smartxontract based erc20 exchange, generates at the moment 10% of the block fee of etherieum. Exchanged values are around 2000000 $ daily. Exchange fee is 0.3%.
This shows many problem of ethereum.
– Transaction is to low. At the moment the standard 4 wei gas generatea transaction interacting with the smart contract are pending forever. If I use thenfold wei as gas, its working, but one interaction then costs around 0.5 $. Way to hight.
Its quite a simple contract, only xxx lines long.
2. Normal user use the web frontend, but on the smartcontract its possible to set the fee level publicy. So It should be possible to pay no fee. The flexibility is limited