We had the super seat and it's waaaaay better in my opinion. It can be used as an infant chair, activity center, and a booster seat when they are older. It was one of the baby items we used most.
Super Seat takes up a ton of room. Considering all the baby gear you have I would go for the bumbo. We fed ds in his when he started purees. It was great to bring along as well and we could sit it on the kitchen table. With close observation of course.
Re: XP: Bumbo vs. Super Seat