For maximum flexible development, use Adobe's Flash IDE itself. Flex is a watered down version of Flash IDE for quick development.Using Flex is recommended only if you cant afford an Actionscript developer. [Actionscript 3 is written almost like Java ]
Twice. Once with an Indian development team through Getafreelancer and then another project with an individual from Romania.
The Indian team did real good job and still provide quality support. The Romanian guy took my money and left. Doesn't reply to my mails anymore.
A friend of mine hired an Indian firm for one of his projects, but he got ripped off.
If you get a good offshore team, its definitely an asset. I am lucky i have one.
Advice[not suggestion]: as far as possible get someone from local area. Outsource to offshore teams only if skills required are not locally available.Taking chances would result in real good waste of time.