From my experience, getting a group of people to see and test your product for the first time is the best thing you could do. Listen to advice and feedback and then use it to improve the product.
I think it's too easy to just focus so much on your own product, that you lose touch in what other potential backers would feel about it. As you've spent so long working on it, you may of missed some functions out.
The same goes for your campaign page. It's best to get as many eyes as possible on the page before you launch it. Make tweaks and develop it.
It's a shame you won't relaunch your KS campaign (try IGG?) but hope it hasn't put you off Crowdfunding