“In my experience, size isn’t everything. it’s how you use it that counts” and “There are a hell of a lot of variables brighter than 16th magnitude.”
Have you thought about monitoring stars for exoplanet transits? Some of their stars are quite bright and within range of a 100mm scope.
Of course, if you send the same amount of money on a reflector as on a refractor you could get a markedly larger aperture … This assumes you haven’t already bought your equipment. If you have, there are still many things you can do with photometry on what you have.