DME generally gets you to your resort 60-90 minutes after you get off of the plane. That would have you to your resort by noon or most likely a little earlier. Your bags should be delivered within three hours of check in, which would be about 3:00 p.m. There's no guarantee you'll be able to get into your room before then anyway, since 3:00 p.m. is check-in time at most resorts (I think it's 4:00 p.m. at the DVC/villa properties).
Stopping to get your own bags will add at least 30 minutes or so to the time it takes you to get to your resort and, as noted, you may not be able to get into your room when you get there. That means a likely scenario is: 1) waiting for your bags at baggage claim, 2) schlepping your bags to the DME bus yourself and 3) storing your bags with bell services/luggage services at the resort. It also means tips for the bus driver for loading/unloading your bags on the bus and tips for bell services to store/retrieve your bags at the resort.
My advice is to use the DME luggage transfer service, but take in carry-on bags whatever you'll need for at least the first day you'll be at WDW. That's a good thing to do even if you aren't using the DME luggage transfer service, in case the airline happens to "misplace" your luggage.
