If I were you, I'd keep them. I'd been lusting after Daltons for years before pulling the trigger on a Walnut Dainite pair late last year, and I couldn't be happier. In my eyes, whatever you lose aesthetically (which, admittedly, isn't much) is more than made up for by the added functionality. They've become my de facto "I know it's going to rain today and I don't feel like fussing with Swims" shoes -- even during the warmer months, despite living in the South.
That said, what works for me may not work for you. Leather-soled Daltons have dropped as low as $219 in the past year, which isn't too much more than what you probably paid for the Dainite, so if you don't think you'll be happy with these and you're willing to bide your time for another significant markdown, that's an option, but to be perfectly honest, given what you plan to use them for, I think you'll come around.