Some how it was a good idea but we all know that it is very risky and in my personal opinion this is not going to work most of the time because in a business if your going to make the payment in a cryptocurrency like a exchanger I think it is going to need a lot of capital and also you need to accept different token or Altcoins in the market which is a bit risky for a lot of people because the market is also having its movement, if you need money for your business you cannot easily sell they Altcoins.
That's right, it's risky especially stable prices, and the OP has already talked about it. Fluctuating prices can be overcome by using stable coins such as USDT to provide a constant price from existing services. However, this goes back to the objectives of the OP, if you want to pay using BTC or ETH or another altcoin, you can make a price benchmark with fiat and then confirm it with the cryptocurrency price right then. Whether it goes up or down after that is the risk, and it can be considered as investment or savings.