Hi Mica,
I won't make enough (or any) money to justify the very expensive license for Antenna House or XEP, thus they are not really an option. I find FOP to be really sub par.
I fully understand. I was exactly in the same situation few months ago and also found ConTeXt as the only option for my needs. Welcome to the club :-)
My basic work flow would have to be DITA XML > DITA OpenToolkit (build process) > ??? > ConTeXt > PDF, where ??? could be some Toolkit XML output, XHTML, HTML5, FO.
In your case I would fork 'dbcontext' stylesheets and adapt them to the DITA vocabulary (reasonable subset). If the Tooolkit is really 'Open', it shouldn't be so hard to integrate this new stuff into it. The build process would simply generate the ConTeXt source file. Even forking of something already done means lot of work so I suggested switching to DocBook instead to reduce this effort significantly. Regards, Jan