RE: Sight lens
Rob just got one from Feather Visions for his Viper, and I've got a Feather Visions lens on the way for my new Spot Hogg Hogg-It that'll be here by the end of the week, so I can let you know after that. He had to send the Zeiss glass to Spot Hogg so they could drill it out especially for my sight.
When talking to Bert at FV, he suggested getting a 2.5 power so that I wouldn't need a clarifier peep (I want the capacity to screw it on and off and not have to change my whole setup when switching from IBO to ASA shoots)... I asked him if that would closely approximate being able to see the target detail about twice as well as with the naked eye, and he replied that I was close... probably less than twice, but I had the right idea.