I don't know if you got the reply you wanted, but I wanted to throw my two cents in on this one. I think you have the right idea about using someone who has been around for awhile, or more accurately, someone with a good reputation.
I frequently send my images in for print, both online and locally. While I know there is a chance someone can misuse my image, when I use a business with a good reputation I feel secure in the knowledge it is not likely to be worth their time to steal or misuse my image in exchange for their good name. If I am in any doubt I Google the name of the company and look for reviews from publications i am familiar with, or check with the Better Business Bureau. If they are good at what they do, a lack of bad reviews isn't enough for me, I expect to see happy customers and reviews shouting about the good reasons I should use this company
I would be interested to know who you ended up using, and if you were satisfied with the results?
~Sometimes you're the fly, and sometimes you're the windshield.