I have used both, and I agree with your analysis. The great thing about MailChimp is that it lets you see the email in different clients. That is really the hardest thing about sending emails. However, you can use that service without doing everything else through MailChimp. Also, once you get the hang of it and develop templates, it no longer is much of an issue.
AWeber finds a healthy balance between ease of use and robust functionality. There are some nice features — particularly in the autoresponder realm — but navigation is intuitive enough that I was able to perform basic tasks without looking up tutorials. When I did find myself at a loss and turned to the online help resources, I was quite impressed with the range and scope of guidance available.
An award winning serial entrepreneur running multiple online businesses with 5 figure income. He is the founder of Webfanzine Media which is the parent company of the largest WordPress carousel portal named SliderVilla, Most popular documentation plugin named Documentor. He is also the founder of PurposeThemes, the largest multi-author WordPress theme review portal with 2,000+ premium and free themes. He spends most of his time on marketing these products and helping new people getting on the most popular CMS platform i.e. WordPress. Sometimes he blogs on Internet Techies which servers 300K+ visitors per month.
Think about implementing referral links to incentivize your subscribers to spread awareness about your brand, too. Referral links allow your current customers to promote trackable links for your business. In exchange for sending new paying customers your way, you can give them incentives like discounts, coupons, vouchers, cash, prizes or redeemable points.