rjs5x5
One of my favourite researchers is Capers Jones. He's been researching software productivity for decades. His current company, Namcook Analytics, published a paper on his recent efforts [1]. Tables 14.1, 14.2, and 14.3 are of particular interest, although the whole paper is well worth reading for its own sake.
Some of his previous work seems impossible to find now. internet bit rot. One stands out in my memory. It also compared productivity in various languages, but also included error rates. Smalltalk ranked equally highly in that work, with significantly lower error rates per line of code.
To answer how Smalltalk compares to what I did previously, I have worked professionally using quite a number of languages, including Fortran, C, C++, and assembler (numerous). I would not willingly stop working in Smalltalk. Yes, it is that good.
Most companies using Smalltalk have exceptionally small staffing associated with their Smalltalk application, often having only a handful of developers & DBAs. Most of these businesses seem reluctant to talk about their Smalltalk applications. It doesn't seem to be due to embarrassment, but rather due to a desire to protect their competitive advantage.
[1] http://namcookanalytics.com/wp-content/uploads/2013/07/Funct...