I would like to know if it is possible to refactor R code in ESS. Using search and replace in Emacs does not seem to be a good alternative to it.
In Emacs you can do a search replace with M-% and then ! will replace every instance in the current buffer.
M-%
!
If that isn't want you mean, can you explain (edit your Q or comment here) what Statet does and what exactly you'd like to do in Emacs + ESS?