Hi Opentoe,
You are right to be wary of experimental software when we are talking about money.
I work to my best effort to make MultiBit as good as commercial software (which is my background) but with the manpower I have available there are limits to what can be done.
In reality ALL Bitcoin is experimental to some degree.
The most important thing with a Bitcoin client are the private keys.
You can export your private keys from MultiBit to a file and check they create the correct Bitcoin addresses in some other Bitcoin application (though be careful exposing your private keys to anyone) or by reimporting them to a new MultiBit wallet and checking the addresses.
The encrypted private key export files can be decoded on the command line using openssl as described here (near the bottom of the post):
https://github.com/jim618/multibit/wiki/Export%20and%20limited%20import%20of%20private%20keysYou don't even need MultiBit to decrypt them.
In terms of code audits probably the best indicator is the number of forks of the code base. There are now 14 forks. This means 14 people have taken the repository and have a copy of the source code on their machine. Of course it is up to them to comment on code quality.
The licence on MultiBit is the MIT licence which is basically 'Do what you like with this code. No warranty expressed or implied'. This won't change as I am happy for other people to use the code as they want and for legal liability reasons.
Re: testing. The testing in MultiBit is at various levels:
+ there are unit tests for low level functionality
+ there are a few functional tests which set up a 'MultiBit runtime' and then actually connect to the Bitcoin network and test something.
+ each release I 'put my test hat on' and run through the basic functionality to regression test it. The results of this testing are the release checklists that I then scan and post on the website. You can see them at the
https://multibit.org/releases.html. Often I spot something that isn't quite right but is acceptable so I fix it later - you have to be pragmatic.
Probably the best path is for you to try MultiBit out with small amounts of bitcoin. Get familiar with the private key export so that you will always have access to your private keys. Judge for yourself.