When does it pay off to use S4 methods in R programming

Question

I program regularly in R in a professional context, and I write packages for clients or co-workers as well. Some of the programmers here have a Java background and insist on

Answer 1

My experience is in line with yours, so I use S3 exclusively.

To clarify: S4 has some slick features (e.g. dispatch on multiple arguments and slot type-checking), but I have not encountered a situation where the features outweighed the costs. Examples of the costs include: any slot change requires a full object copy and (potentially worse) the on-going changes to S4 Methods.

In short, I like the idea behind S4 but I would wait for it to mature before using it in my own code.