It will be quiet interesting if you'll use Bitcoin & Ethereum at the same time as a payment method. For faster transaction if it's peer-to-peer or third-party-programs; you might wanna recommend to use Ethereum for quick transaction. In the other hand, Bitcoin is kinda sluggish for blockchain transaction.
Who says Bitcoin is a bit slow for blockchain transactions? even at this time Ethereum transactions that have a lot of pending unless someone uses a slightly higher fee when making a transaction so that the transaction can be successful more quickly.