I use the capsules, too, mainly to keep things clean and neat... FWIW, IMO, the main difference with using them insofar as performance goes, is simply "time". The more time on the temp setting you choose, the more conduction will do its thing and heat the material through contact with the aluminum; this sort of makes up for true unimpeded airflow you'd get without the cap, where convection does more work. It just seems to me that using caps increases conduction and decreases "air contact" with the herb, and
therefore takes time to get the herb uniformly heated through.
Before S&B, I was used to being able to microdose with ROFFU or V3P, as I said earlier, using
@RustyOldNail 's suggested method of dumping the cap to cool between the maybe 2-3 "sessions" per capsule. But microdosing is harder to do with Venty/Mighty; capsules help in that regard, with the mild tradeoff of introducing more conduction than convection.