I'm afraid I can't offer much more than has been said. The main reason for my post is that Vortex is offering a $50.00 rebate straight from the factory. If you go to the Vortex website, you'll see it there.
I recently purchased a Viper 6.50 - 20 X 44 PA, with side mounted parallax adjustment. I have it mounted on an AR 15 carbine. I haven't sighted (fine tuned) it in yet, but all appears excellent.
There are many things that impress me about this scope. The main thing (so far) is the build quality. This scope is really built heavy duty. It appears it could take a lot of abuse, and come out in fine shape.
I have a Leupold 6.5 - 20 X 40 long range with 30 mm tube mounted on a 20" AR rifle. I have killed many, many PD's with this set up. The reason I bring this up is because the Leupold visually appears to be a lightweight build compared to the Vortex. Don't get me wrong, I love the Leupold with the varmit hunters reticle, it's just a lighter weight build than the Vortex.
If the Vortex shoots anywhere close to the Leupold, I wouldn't hesitate to buy another one, as long as their price structure remains close to what it is now.
I called the factory twice with questions about the Viper, and was treated with nothing but the utmost courtesy. They didn't try in the least to hurry and get me off the phone, so they could move on to the next call.
Within the next month I should have it field tested thoroughly, and will report back on the results !!!!
The only complaint I have so far is that the Viper is HEAVY. But of course anything built that heavy -duty, is bound to have a weight increase.
AS I said if the Viper shoots anywhere close to the Leupold, I will have found my new scope of choice. At their prices, I just don't see how you can beat it with another brand. I'll report back in about a month with the range results.
Hope this info helps you in your decisions.
Hangtime.