First off, thank you for the compliment 
We have looked up to Mailchimp for a long time (and continue to) so it’s flattering to be mentioned alongside them as a company to aspire to.
The angel money we raised helped us hire two experienced folks and brought us a small network of advisors. As you probably know, it’s generally quite easy to get advice as we’re thankful to work in an industry where many folks like to pay it forward. The hiring was quite helpful and it may have taken us another year or two to build up enough revenue to hire someone else. But really, most all of our growth was funded by customer revenue because by the time we got to PMF we were nearly out of cash. 
If we were doing it again, I’d try to only raise money to fund efforts to meet demand. We raised money before we had fit in the market and I’d try to avoid that unless absolutely necessary. If we were to raise money, I’d look at structuring a round similar to what Indie.vc offers — have a preset way to buy equity back from investors so if you want to run an independent, profitable company for the long-term you have a clear path to doing that from the start.
I think it’s awesome that you’re going the bootstrapped route. I think being forced to make it work on customer revenue produces really great products, resilient businesses, and pragmatic founders. 