I'm going with the 990 but am not opposed to trading in my F350 SRW for a F350 DRW if I can find the right deal ;) I've only got 42k miles on it and it's worth about $32k on trade in so I can probably get a decent deal moving into a DRW if I find the SRW just doesn't feel right going down the road.
I'm looking at options but will start with the SRW with all the upgrades I can put on it (within reason, I'm not putting 19.5" tires and wheels on it or I might as well spend the money and get a DRW).
I got the SRW because I drive offroad a fair bit and felt the DRW might be more trouble in the snow offroad etc