"checked and safe"
Safe? The coins go peer-to-peer, directly from the buyer to the seller wallets. The seller can use any wallet they prefer and we never come into contact with the coins, unlike the vast majority of services out there such as Coinpayments or Bitpay. I don't understand what could be safer?
"I would always take x% transaction fee than xx% yearly."
We don't charge any yearly percentage. It's a flat-fee for unlimited transactions per year.
Why would you prefer a % per transaction and numerous TXs?