vendors using Bitpay et al are essentially just accepting fiat and perhaphs an unknown % of BTC too (most companies would keep this % to themselves for obvious reasons)
Hm, what would be those reasons? For tax evasion? It would be quite risky, since Bitpay knows how much the vendor received, and even a traditional audit of his books by the IRS could easily reveal the evasion.
By the way, I am aware that this discussion is old and my observations have been made by others before. However, there still seem to be people who expect the price to rise whenever such news come out, or claiming that the route USD-->BTC-->USD-->Goods saves money compared USD-->Goods.
You make a lot of assumptions, and then you continue to argue those assumptions in spite of contrary facts. People can weigh the costs, and determine which route saves more money. Ultimately, BTC is going to be cheaper for transactions as liquidity increases. Dell creates additional liquidity for BTC transactions and potential snowballing of adoption.