Also, the Lua version used in Grim was 2.5 (!) and a major issue was the lack of cooperative multithreading (see http://www.grimfandango.net/?page=articles&pagenumber=2).
I don't know what version was used in Escape from Monkey Isand (3.1 ?), but the current version of Lua also "runs in circles" around the Lua that was used in those games.
EDIT: more by Bret on Lua in Grim: http://www.slideshare.net/hughreynolds/lua-patient-zero-bret...
You probably wouldn't use SCUMM for anything except an adventure game, but in that particular case I think it would be much better than a general-purpose language as LUA.
There's a programming language for writing textual interactive fiction games, Inform 7 ( http://inform7.com/ ), which reads as a natural language. For example, here's part of the "programme" of a game (copied from http://www.hpiweb.com/newmedia/i7/cbrk/source.html )
The Forest is a room. "This forest is cold and damp. Sunset is drawing very near and shelter must be found soon. The only apparent direction to go is north." A room called Before the Castle of the Big Red Key is north of the Forest. "The castle looms before you. Its massive front door has a lock that seems to glow a fiery red. You must continue north past that door. The only other exit is to the south." The big_red_key is here. The description is "It's a big red key." The printed name is "big red key". Understand "big", "red", and "key" as the big_red_key. It unlocks the massive front doorway. The massive front doorway is north of Before the Castle of the Big Red Key and south of the Castle Vestibule. The doorway is a door.
It would be interesting to have a graphical equivalent.
Of the few SCUMM script examples I've seen, I can't seem to understand what Gilbert means when he says: "It did things Lua could never dream of." The ability to control a C64 from a UNIX box? That actually sounds a lot like Naughty Dog's GOAL: https://en.wikipedia.org/wiki/Game_Oriented_Assembly_Lisp
And according to one experienced source (OP): The answer is a resounding "yes"!