A coarse pitch prop will have less flight drag than a fine pitch prop, but not a lot less, compared to being feathered. Definitely, coarsing out a CS prop makes a difference when you're gliding a single, but no where near as much difference as feathering it. In a twin, if the engine stops running, (and you're not going to get it running again) you must feather it. If you select coarse pitch without feathering it, yes, you'll get a little less drag, but an increased likelihood that the prop will stop turning, and then you won't get it feathered at all. At that point, stuck in coarse pitch, you're in trouble.
I have spent hours flight testing this on the Lycoming DA-42, Twin Comanche, and Navajo during propeller change approval work. In many cases I found that an engine shut down with the mixture and the plane around Vmca, if you did not feather promptly, the engine would stop completely, and could not be feathered after that. This was my common experience. A starter restart was my only option at that point, because it would not windmill start, if it had stopped. With lots of altitude, I could sometimes dive it, but this is a very risky waste of altitude.
One of the few single engined aircraft I know of, which can be feathered in flight is the Caravan. I have feathered and glided them may times during testing (to eliminate "P" turbulence under the belly for a minute). The difference between coarse pitch glide, and feathered drag is incredible. So having had that experience, I would never want to be stuck in coarse pitch in a twin, if I could get to feather.
For those who read the article, twins on one engine can be very marginal - and that's with one feathered. If it's not, that really marginal performance is very compromised, so may be negative.
I flew both the C 310R, and the C 303. The 310R had six fuel tanks, which certainly must be carefully managed (so yes, you could run out on two of six, if you don't reselect, and you could even pump fuel overboard, if you go ti wrong). The C 303 had only two tanks - left and right - On or off. In the 310, you could manage the fuel on a long flight so as to safely run four of those six tanks dry. The result was that the uncertain fuel quantity in the remaining two tanks was a much lower percentage of the total fuel, so your fuel quantity planning could be much more precise, and less worrisome. Or, in the C 303, you could watch the two fuel quantity indicators bounce under 1/4, knowing the accuracy of some Cessna fuel quantity indicators, and knowing that you're not seeing the coast of Iceland yet - that made me nervous. There are also excellent structural advantages to the 310 multi tank system. I'd rather learn to, and then manage the fuel to gain those benefits, than to get ot be lazy, and suffer a system with less utility.