There are arguments for and against paying the ransom, as stated here http://www.coindesk.com/fbi-malware-victims-should-pay-bitcoin-ransoms/. Thinking through the Aria scenario, I might consider paying the ransom, wait for the bitcoin to move around, then offer a bounty. Ethical hackers would love this.
I might even suggest the FBI is recommending people pay the ransom, as they are working on a way to track down btc transactions. The more transactions that occur, the more evidence there will be to track the perpetrators. Even though the blockchain records all the transactions, there may or may not be sophisticated enough software to follow where they go, through mixers and such, but I'm positive such software is coming.
Eventually, if you have bitcoin, you want to be able to spend it. Spending it requires you to identify yourself in one way or another. Combine that with the inevitable blockchain trail of all transactions, no matter how you attempt to mask or mix your transactions, there will always be a trail to follow and given enough data someone will always be able to figure it out or even narrow it down to just a handful of people.
I always thought that kind of odd. It seems as though everyone has it backwards. Cash is totally untrackable, and as "anonymous" as a transaction can be. Bitcoin is totally transparent, there is just not an "easy" or sure way to track it, as of now. You can be sure it is coming. In reality, bitcoin is the POLAR OPPOSITE of cash. With the proper software, and enough computing power, any Shatosi ever sent could be tracked. It won't be long, cash will be looked upon as the "stuff the bad guys use", while bitcoin will eventually become totally trackable and totally transparent, if someone wants to take the time and effort required to do so. When that happens, the "bad guys" will not be able to use it to help them break the law.
Smokey