The only qualm I would have with cutting DRs completely is that sometimes you are put in situations where you will drastically need to tip the scales. LEDless as it is already has a somewhat difficult time (barring the help of godly dredges) against quick aggro. I know that if Zoo ever gives me the chance, I will go ape-shit and dump as much stuff into my yard as possible just so I can get as many zombies and a DR target into play before they untap and find a way to remove my bridges. Your ability to generate more zombies right then and there will be limited only to how many Therapies and Ichorids you have sitting in your yard. Sure your opening hands might be better, but when you really need to get the ball rolling, the option won't even be there.