> window based tools don't seem to have much advantage compared to e.g. SLIME, isn't it?
One advantage for a lot of people is that other IDEs don't use GNU Emacs. That's an often requested feature. Another advantage is that one gets more developments tools, incl. various browsers, a GUI toolkit, an interface builder, more native look&feel on platforms like Windows/Linux+Gtk/macOS, ...
Allegro CL has syntax coloring, but not in the web version as it is now.
