Yes pumice not cheap to ship but will outperform vermiculite by far and perlite performs better than vermiculite but its stll not anywere near the performance qualitys of pumice, the pots will for sure be heavyer but for more heatlhy roots pumice is unmatched and its still lighter than sand and/or gravel much less dence.
Tell that to my trees. I've had to top this 11' cocktail citrus tree about 4X since it froze back to a stump Jan. 2018. It is loaded with limes and oranges. Left side, rear corner.
Tree in the front, left side of photo, is a 8' Sharwil, Lamb Hass, Pinkerton grafted tree from last year that also froze back to a stump. It's a good 8' wide and growing like a weed. I hope to get a heavy fruit set next year. Am rebuilding now.
Frozen back Reed stump, March 19 2018 pushing some fresh shoots.
7 months later, 10'. I've had to top it twice when it hits 13' at my roof!
I gave up on perlite because the dust is hard to deal with and it's so fragile, falls apart when shipped and handled. That once "Coarse" grade soon becomes a "Fine" grade. Vermiculite contains some beneficial elements such as Silicon, is light and doesn't break down thereby maintaining an open soil structure.
To each his own.......