RE security - we don't actually hold any bitcoin and our ACH provider handles transactions; we're trying to steer clear of all major security issues by avoidance. We've put a lot of effort into securing any data we do have, though, and we've also got a great compliance and legal team working with us for the finance issues
For example a bitcoin based payroll is like giving away shares (less volatility of course, but you get the point). If someone would work for shares, he probably will (think about) accepting bitcoin as payment.
In Silicon Valley people takes risks easily, but in Europe I think no one in their right minds will wanna do this.
Payrol automation on the other hand, especially for software companies makes a lot of sense.
The risk of getting paid in BTC does exist as far as price volatility, but it's not a far cry away from being paid in cash being as it's liquid and many merchants accept it as payment.
USD on the other hand devalues over time by design. So these two currencies are designed in totally different style and both wouldn't exist if they hadn't been designed that way (USD to devalue over time and BTC to increase value over time).
So assuming that the employee isn't going to spend it and that BTC is forever increasing in value over time - the employer isn't giving away a valuing asset because they purchased it and gave it away within a few moments while the employee gets the benefit of a valuing asset. I don't think anyone would complain about that.