should help you find a specific post
Short question, long answer and opinions will probably differ.
Well replacing with will increase the damage that attack will do on the enemy camp.
This is interesting if
a) that attack is part of a block, where time is an issue and
b) if it allows you to defeat the camp using 1 wave, since then you won't have to wait for your general to recover (some players have a lot of generals and rather let a general recover then loose more expensive troops)