Yes, it is possible. I know a few people who use gear swaps as WHMs as well. Personally, I don't like using gear swaps because with how finicky the server is right now, it doesn't always work right. Sometimes the spell won't start casting, sometimes the gear won't switch back, sometimes the gear won't equip. Changing gear also roots you in place while the animation happens, which isn't too big of an issue, but on stuff like Ifrit if you're changing gear that often (like on every regen cast) you're probably going to get unlucky at least once and have an eruption spawn on you as you change gear. As it is right now it's just not worth it in my opinion.
