I'll second the ammit RDA. I've got one and I love it even though I mostly DL. It would be perfect as a tester for you recipe's
The ammit is the only mtl rda I have. I love it for squonking because of how the AF is. It's practically leakproof. From my experience the top cap isn't the best for taking off and on. If you have a thin bore 510 and you have to remove the cap to drip it could be a bit of a pain. It could just be me tho.
@Redbird11 For durability, capacity and portability, you can't beat mech squonkers and rdas. They are my main on the go devices. If you need a good tough mod that will last through years of abuse, I highly recommend them.
You don't need to fall down a rabbit hole with them but having one or two on hand might be a good idea in case your other gear fails and replacement parts are unavailable