Soliciting dApp Feedback, Would You Use A Steem Marketplace?

Unbeknownst to most, for the better part of a year I have been working on a marketplace for the Steem blockchain. It hasn't been a year of solid development, just bits and pieces through times of inspiration and when I am not busy.

I am in the process of getting a plan in place to finish it and I would love to get some feedback about what you would and wouldn't love to see in a marketplace.

1. Would you sell items on a digital marketplace, transacting only in Steem?
2. How important is escrow and would you expect this to be free or would you happily pay for it as a seller to protect buyers?
3. Would you expect the service to work on desktop as well as portable devices such as tablets and phones?
4. What other marketplaces have you used before? Shopify, eBay, Big Commerce...
5. Transacting on an online marketplace with your Steem account, what are your biggest concerns?
6. Have you sold anything online before?

Please feel free to let me know what you would like to see in a possible marketplace running on Steem.