Well, we are going from an "all operations on one potentially massive transaction" to a "god knows how many transactions" approach.  

I haven't performed any tests on how faster this approach is compared to aggregating some operations onto the same transaction. It does have a considerable impact over the first approach for large sets, but that was to be expected.

Your concerns are valid, but bear in mind that if this function should never handle more than one update anyway, and full maps can be large too.  It's not that adding the config option would be that much extra work; I just wonder if it pays off under normal monitor behaviour.