It doesn't impress me as being all that hard to find most combinations, I recently decided to try out a flipper with a thumbstud and hole (Eafengrow EF914). While it's not my ideal knife, the stud and hole work such that I end up using both at once, and I can use them and the flipper at the same time too, so none of those are necessarily surplus, and I like that aspect of the knife a lot. What I'm a less sure about is how those things would work with a front flipper. I can't imagine trying to use two flippers at once, and using a front flipper along with a stud or hole seems like it would be relatively awkward. It would offer you another option, but I'm not sure that they have much synergy as a combination, and they might be uncommon for that reason.