Although I have not tried an 8-3/8" specimen, I can tell you a little about the 460V.
I bought mine used in December. The recoil is a little more punchy than my 6.5" 629 Classic. I thought it would be alot worse than it is, but it still makes sure you are awake. But the percussion you feel when you shoot is significant. It slaps you in the face like a cheap saturday night hooker.
I do not have an optic on it, nor do I intend to install one. It is currently at my LGS getting the Meprolight front and rear night sights installed. http://www.meprolight.com/default.asp?catid={4EA2FDEC-39B1-44F5-9CAC-ECEBEEBA0264}&details_type=1&itemid={D7C12EAA-DE12-4334-9960-730075D4F404}
I am looking to get the best possible open sight picture I can with this revolver. I like how relatively compact my 5" X-Frame is and want to keep it that way.
Being you are thinking for using for protection while fishing and such I would highly recommend this rig:
Guides Choice Chest Holster, Original Alaskan Holster
I bought that rig and what little I have carried my 460 in it, it carries unbelievably easy and comfortable! I highly recommend this rig.
Now, since we are still locked in the dead of winter here in CNY with cold temps and snow that just won't quit, I have not yet done any longer range work with this revolver. I have only done work-ups and testing for accuracy up to 50' at my rod and gun club's 50' indoor range. Once spring decides to get here, I will see what I can do at the outdoor 60yd handgun range.
I understand you were looking for someone has at least used both sizes, but I figured I could at least give some input on the 460V.
Good luck with your decision!