I market them as a Hybrid call wood/acrylic.
If you're buying their inserts that cost just a few dollars, they're not acrylic. They're molded polycarbonate. They sound good, but they're definitely not acrylic...Hence their price.
Woodnquality, if you're wanting to buy an Echo call made by Echo you can't go wrong in my opinion. They're production calls and are far from custom, but there's no arguing that they make a darn good sounding call. My first duck call was an Echo cocobolo single reed timber and it is just an awesome call. I now have a taste for custom calls but as far as production calls I think they're unbeatable.
If you're looking for which Echo polycarb inserts to buy for your barrels, I'd say get at least a couple of each and try them out. They are hardly an "investment" at a few bucks each. Nothing wrong with giving a customer some options. I like their double reed timber most but haven't blown an Echo I didn't like.