Never tried the grout stick, so couldn't say. I use a Stanley paint pad (not the cheap ones) and use the edge on grout. You can get into the recesses easy with it. And when it's used you just cut off the edge and you've a fresh edge for the next job. You can get a few applications out of one pad then. Just make sure you are wiping the tiles down a couple of minutes after each grout joint has been done (but you probably know that anyway).
The good thing about Aquamix Sealers is that they are water based polymers (apart from Ultra Solv) and don't smell the way solvents do, which is really beneficial in enclosed spaces like bathrooms.