If I bought a Letus Extreme for the HVX (82mm thread), then bought a 82mm>72mm stepdown ring for my HPX170, would it be pretty much the exact same as buying the Letus Extreme for a 72mm thread?
Yes, it works brilliantly. Check out our short "Cold Calls" for what you can expect from that combination, that's what we did. HVX200 Letus Ultimate, 82mm thread, using an 72mm-82mm step-up ring and shooting on an HPX170. http://www.dvxuser.com/V6/showthread.php?t=150933&highlight=cold+calls