We look at the data on everything, so I do know this to be true (at least for the services we've tested).  Our tests have been conducted using various payment options such as Paypal, Bitcoin, and net-30 terms.  Of course every business is different, so I can't say for certain that our results would be externally valid for every business out there.  Different target markets might behave differently.  (We have seen a similar effect in other areas of choice, for example if a product comes in multiple colors, there can be a statistically significant conversion rate increase by actually eliminating some of those choices.)

Regardless of whether these results would apply to all business types, it remains a reason that we will not be supporting more than one crypto-currency, and the one that we do support must have sufficiently large usage to justify providing the option.