The supercabs are awesome, I would probably have one as a dedicated offroad toy. Ive had a few extended cabs in the past and theyre fun when its just you and one other person or people can squeeze in the cab. Depends on your needs for the truck. For me, its a nice 4x4 to go to the lake, offroad trips, and mountain trips. You get a lot more space with a supercrew to take people places, put dogs in the back if you have any, and you get increased towing capacity.
The money savings is nice though, just depends what you plan to do with the truck. Ive always wished I went crew cab when I had extended cab. If you have an suv for trips with more people then maybe your needs are different.