Last spring I replaced my bag of the last decade. Having perused the bag section at the store before, I intended to buy the 4 Series. One more look-around and only Sun Mountain caught my eye, but I agree I just didn't feel like I could trust going another 10 years with the same bag after feeling the materials and zippers...
Stuck with my original choice of the 4 Series and as a walker 90% of the time I really dig the insulated bottle pocket. The only negative with the bag as far as I am concerned, and others have mentioned, is that my clubs tend to get tangled way to easily down at the grips. I might have to buy some of those plastic tube dividers and cut the appropriate length off the bottom so they sit under the lip of the bag and don't visually irritate me as much. They sure are expensive for what you get though. Anyone have alternative solutions?
And to answer the OP, I believe you get 1 or 2 more side pockets, 1 more front lower pocket, and no insulated bottle pocket with if you were to go with the Hoofer, compared to the 4 Series. The 4 Series has a slightly smaller over-all profile and I don't carry much in my bag, so if you don't need it, why pay more?