I use the metal tube for the ants. Shorter distance they have to travel to the collection vial, and lesser chance of them grabbing onto the metal tube than the silicone tubing. (I have the THA version, but I assume it's the same/similar to what your talking about.)
Currently kept species
L. neoniger, P. occidentalis, C. modoc, C. novaeboracensis, C. vicinus, T. immigrans, A. occidentalis, S. molesta, P. imparis, M. kennedyi, M semirufus, F. pacifica, P. californica, M. ergatogyna.
Previously kept species
T. rugatulus, B. depilis.
Looking for
Myrmecocystus pyramicus, Myrmecocystus testaceus
Pheidole creightoni, Pheidole inquilina, Crematogaster coarctata, Crematogaster mutans
My youtube channel. My ant Etsy store - Millennium Ants