Which post function to prefer?

[Michael O.]

We have Script Runner installed, so when I want to set the value of a custom field in a post function I seem to have two choices: a) Update Issue Custom Field or b) Set Field Value to constant or Groovy expression.

Which one should I use for this simple case, any difference in performance?

If I need to set multiple custom field values, is it better to have let's say 4 simple post functions of type a) one for each field, or should I combine all 4 into one groovy script using a Script Post-Function?

[Randy]

Honestly if i can get by with using the built in "Update Issue Custom Field" post function i'd use that over the SR solution b/c it'd be easier to maintain and clearer when you look at the post function list what's happening on transition.