Some people think small cell fndn helps control mites.
My comb is all small cell or foundationless, and I've never had mite issues... but I don't know ir=f the SC foundation has anything to do with it, as I've never used large cell.
It may be the genetics expressed in my bees.
Or a combination.
Or something else entirely.
If you use both large and small cell, I wouldn't expect to see small cell benefits b/c there are many large cells present.
Using both sizes is no worse than using all large cell, at any rate.