The members I've listed have all been active, reliable, and helpful on this forum for over a year.  You can read through their posting history and see that they've built up a significant reputation for themselves here.  They've engaged in many transactions of significant value and have acted in an honest and trustworthy every time. There is no guarantee that a person won't suddenly decide that it would be a good idea to destroy their reputation and run off with someone's funds, but your risk is significantly lower with someone who has put a lot of time and effort into maintaining a good reputation than it is with a newbie that has no reputation to be concerned.

Due to the nature of cryptography, there are also some methods of generating transactions that reduces risk even further. Using these methods, theft would require collusion between the escrow holder and another party in the transaction.  There is a method using EC multiplication that was described by Casascius and it can also be done with 2 of 3 multi-sig transactions.

If you have a PayPal account, I believe you can load the value from the GreenDot MoneyPak into your PayPal account.