Kanika recently asked, “When do we use ‘rather than’ and when do we use ‘instead of’?”
The short answer is that in most cases, the two phrases are interchangeable, although “rather than” often has a more formal tone than “instead of.”
The American Heritage Book of English Usage offers a much lengthier answer:
The phrase rather than consists of an adverb and a conjunction and often means “and not,” as in I decided to skip lunch rather than eat in the cafeteria again. It is grammatically similar to sooner than in that it is used with a “bare” infinitive—an infinitive minus to: I would stay here and eat flies sooner than go with them.
Rather than can also be used with nouns as a compound preposition meaning “instead of”: I bought a mountain bike rather than a ten-speed. But some people object to this use, insisting that than should be used only as a conjunction. They therefore object to constructions in which rather than is followed by a gerund, as in Rather than buying a new car, I kept my old one.
In some cases, however, rather than can only be followed by a gerund and not by a bare infinitive. If the main verb of the sentence has a form that does not allow parallel treatment of the verb following rather than, you cannot use a bare infinitive, and you must use a gerund. This is often the case when the main verb is in a past tense or has a participle. Thus, you must say The results of the study, rather than ending (not end or ended) the controversy, only added to it. If the main verb was in the present tense (add), you could use the bare infinitive end.
Curiously, when the rather than construction follows the main verb, it can use other verb forms besides the bare infinitive. Thus you can say The results of the study added to the controversy rather than ended it.
The overriding concern in all of this should be to avoid faulty parallels, as in sentences like Rather than buy a new car, I have kept my old one and Rather than take a cab, she is going on foot.
Clearly, it is grammatically defensible to follow rather than with a gerund, but if you prefer to avoid the controversy, use instead of with gerunds.