There is no transaction fee for Dwolla whether or not you use the free product or the white label product. There is no limit to the number of bank accounts you can debit or credit via ACH with the white label api - https://www.dwolla.com/white-label
It depends what you're trying to process. Keep in mind Dwolla is it's own network. It doesn't process VISA/MAST/ other like Stripe. In theory Dwolla is another payment form that could easily be built into Stripe but the two do very different things.
Using both obviously gives you the ability to do cc/debit transactions for those who want and have the upside of when someone pays using Dwolla.
All in all it's a good move and the system to do it really is not all that complicated. It will be interesting to see the user experience side of things since this has already been available in FI's for years under different names.
Am I the only one thinking this might just be a white label of a solution they were already all using?
The thing that always worked great for me was to buy my competitors product, take it apart, and see who made it or look for names / SKU's / notations I could google. You may be able to find this out just by browsing OEM web sites who advertise their clients.
From there I always had a great starting point for where to start looking. I did this largely because I never wanted to be the test pilot for a new OEM after some bad experiences.
Always visit the factory... It's the best money you'll spend with this sort of project even if you don't give them a PO.