My experience was pretty close to yours, and I agree with almost all suggestions you have made during you feedback. I just disagree with the party increase:
It would make the combat slower, it will demand you to manage one more character (4 gives enough work) and my experience on D&D is that you should always bring a balanced party but not necessarily a perfect one. Been honest, when you don't have one or two specific niches you can work around the challenges with what you got, and sometimes, it's even more rewarding since you fell good with you idea/solution.
