I don't have any specific knowledge of Davidson, but I would be VERY leery of using a marketing company to take over a project while they bleed you dry of money. I would look at their record. The research I had done several years ago showed that less than .003 of submissions ever recoup the outlay of costs when using this type of company. Depending on what you need for a proof of concept or prototype for your particular idea, if you are creative I'm sure you can do it yourself without hemorrhaging cash.
If you project involves plastic parts I can point you in the right direction or at least give you suggestions if you want.
Send me an email if you want any input. email@example.com
If you don't have a nondisclosure agreement I can send you one that you can modify to fit your needs. In the email give me a GENERAL field of your invention. ie medical device for breathing, board game, golf training aid ect. I am under a few nondisclosure agreements and I would rather not have two projects of the same nature.