More iron, magnesium, and potassium than sweet potatoes if I remember correctly. A large russet will have half a dozen grams of both protein and fiber too, though I'm not sure how that compares to the sweet potato.
Two reasons you shouldn't worry too much about the high GI:
First, you ideally are using them for post-workout meals, and therefore the insulin secretion you'll stimulate is ideal. If you're eating a bunch of carbs outside the workout window, it probably won't make a big difference if they're sweet potatoes from a fat loss perspective.
Secondly, you probably aren't eating skinless baked potatoes by themselves, which is what the GI is based on. Ideally you have a large piece of meat with it as well as veggies and butter, chives, cheese etc. The fat, protein, and fiber will all severely slow the digestion of those potatoes.
Personally, potatoes and eggs is probably my favorite post-workout meal, and the large amount of pure glucose always finds its way right into my muscles.