I'm a fresh user of SFK (really great tool!).. So maybe I overlooked something.
But for me, it seems that the sfk replace "-firsthit" option only works with 'same length' patterns (using the current Base version 1.6.5 for Windows). So, when the search and replace strings have different lengths, sfk always replaces all the occurrences, not just the first one. Is that correct? Or was someone successful in using "-firsthit" with different length patterns?
Maybe the documentation could be updated with that (if it's really a limitation of "-firsthit")..
that's correct, it is not yet implemented with variable length replacements. this will be fixed.