I'm a consultant, not a developer, but I've worked with both boomi, suite talk, and web services restlets. Here's the deal with boomi vs code neatly summarized: self maintenance. Get the client able to support themselves 90 percent of the time versus requiring coding changes. I lean boomi hard for that reason. Fortunately I work in a consulting firm where I don't have to be the expert on it though, so I've never had to do it from ground up.

This is 100% true. We use Celigo over custom scripts for basic integration needs so non tech staff can see field mappings, failures and scheduled executions without contacting the tech team

I agree. However I'm rarely involve in integrations that can be handled by non-technical folk or any sane graphical field mapper.