Yeah, Factor's environment looks really similar to something like Smalltalk. The thing with Forth is that it looks really daunting to perform higher level tasks that I'd be interested in performing on a day to day basis.
I find it better to think of Forth as a clever Macro Assembly language for a two stack VM.
When used as designed, one does not actually program in Forth. You first write a tiny "language" and program the App in that.
Not a popular choice today.