A complex application written with CLOS will generally not be portable to Emacs Lisp. An application written in Emacs Lisp that takes advantage of dynamic scope won't be easy to port to Clojure. A library in Clojure that wraps something in the JVM ecosystem won't work in Racket. And something written in Racket using continuations or Pict generally won't be easy to port to Common Lisp.
And even with closer Lisps than that, I have enough experience of "that should be easy to port" then blowing up over minor details to be suspicious. Sometimes it will be 10 minutes.
Sometimes it will be several weeks and incomplete even then.
The latter happens often enough that, the developer's confidence notwithstanding, the average is waaaay longer than the estimated 10 minutes. (The phenomena of tasks being rarely faster than we thought, but roadblocks can be unlimited in extent is generally true in programming. This is one of the reasons why our time estimates tend to be systemically low.)
I've done this. I've seen other people do this. Sometimes it works. Sometimes it doesn't. Sometimes it works fine for the demo but then has weird failure modes that you trip over in production months later.
It may be the right thing to do. It may be feasible. But a general "10 minute job" estimate is laughable.
A complex application written with CLOS will generally not be portable to Emacs Lisp. An application written in Emacs Lisp that takes advantage of dynamic scope won't be easy to port to Clojure. A library in Clojure that wraps something in the JVM ecosystem won't work in Racket. And something written in Racket using continuations or Pict generally won't be easy to port to Common Lisp.
And even with closer Lisps than that, I have enough experience of "that should be easy to port" then blowing up over minor details to be suspicious. Sometimes it will be 10 minutes. Sometimes it will be several weeks and incomplete even then. The latter happens often enough that, the developer's confidence notwithstanding, the average is waaaay longer than the estimated 10 minutes. (The phenomena of tasks being rarely faster than we thought, but roadblocks can be unlimited in extent is generally true in programming. This is one of the reasons why our time estimates tend to be systemically low.)