My understanding is that, without a wick hole, the fineness of the mesh becomes more important. Is that correct? The story I was told was that the means of pulling liquid up is different with a finer mesh packed tight than with a coarser mesh with a hole. Is that correct? If so, it seems 500 tightly rolled is preferred and I'll try and pick up some 500.
Basically what it comes down to is, no matter the circumstances, assuming the same
device: the more layers of mesh making up the wick the better the wicking will be, and a tightly rolled 500 mesh will always wick better than a tightly rolled 400 mesh wick, which in turn will always wick better than a tightly rolled 325 mesh wick etc. It doesn't matter if it's PG or VG or a mix. User BJ43 carried out tests in his
500 SS Mesh/Myth Busting thread that substantiated those claims. It's a fantastically good thread about genesis
devices in general and a particularly good thread to read and follow when it comes to evaluating wicking methods and claims.
That doesn't mean there isn't room for other ways to make wicks. Ultimately, whichever wick works the way you want it to work is the best wick for you, but as far as SS mesh acting as a
wick rather than a juice pipe in bottom tank RATs it basically boils down to having a wick as thick and tight as your device can manage using the finest mesh you can get your hands on.