Flawless plan? Depends on perspective. If you don't mind paying your customers 20% to go learn about bitcoin and become a user, it's a great idea. A very noble donation and great contribution to the community. It is the spread of adoption that is driving value now, and that needs to continue...so it may be in your long term best interests.

From a myopic, immediate self interest perspective, of course it makes sense to take 100% fiat and buy 20% worth of ฿.