Nothing to write home about. Most of the time I'm developing inside of LispWorks, but because I'm so used to Emacs and I'll be using org-mode and magit anyway,

Nothing to write home about. Most of the time I'm developing inside of LispWorks, but because I'm so used to Emacs and I'll be using org-mode and magit anyway, having a Slime session as well to try out stuff and run tests comes at no cost. Simply compiling something with SBCL catches some stuff, and it's always good to make sure your code works in different implementations during actual development and not as an afterthought. Besides, as clunky/spartan as they are, Slime and Sly are a lot of fun so why not? Even good old Hemlock gets some use. When developing I always detach the UI code so it lives in its own package, where I don't hesitate to make use of implementation goodies such as CAPI (of course) and the mp package. The rest of the stuff aims to be portable CL and uses the de-facto compatibility libraries.