[fiddlerwoaroof]

For a lot of things there are portability libraries that bridge vendor extensions between implementations. So, in practice, you can use features that aren't part of the ANSI standard (threads, sockets, ffi) without tying yourself to a single implementation. Also, FFI is pretty trivial in most implementations.

[exdsq]

Cool! Thanks for your response. So would you suggest Lispworks as a good development environment for new Lisp hobbyists who aren't keen on Emacs?