It's been almost 10yrs ago that I put a 6 Dasher bbl on my insurance agent's Savage, but I still recall being pretty disappointed when I looked through the SS20x42 scope he'd mounted on it. I'd been doing most of my LR prone HP shooting with a SS16x42 at 1000yds, and never really felt under-equipped. But his 20X SS was way dark compared to my two 16s, so unless they've made considerable improvements to those scopes over the past 10yrs, I'd stay away from the SS20.
Since that point in time, I've gotten more into the PRS-style side of rifle shooting, and worked my way up from a Vortex Viper 6-24x50 PST to several different 34mm scopes, including Bushnell 3.5-21x50 ERS, Weaver 4-30x56, Kahles K624i AMR, and most recently, a couple of Athlon Cronus 4.5-29x56. Along the way, I've had opportunities to fondle high-end scopes from S&B, Vortex Razor Gen I&II, Leupold Mk8, NF Beast, & Premier. My favorites are the Kahles - great glass, excellent tracking, very good turrets, and I've really learned to like & use the AMR reticle. However, these scopes retail for around $3k.
Like I mentioned, I've had a couple of Athlon's top-of-the-line Cronus scopes for several months now, and have had opportunities to compare them side-by-side to my Kahles scopes while shooting at 600yds. I've been very pleased with the optical quality of these new scopes, as well as the tracking and the reticle. All the 34mm tube scopes I've seen & used are mil/mil versions, and based on how well .2 mil dots or hash marks work, I'd never go back to a plain old mil dot reticle. Athlon's MAP for the Cronus 4.5-29x56 is around $1700, which - when you consider the optical quality, reticle, zero stop, and tracking - is a very good value. I went away from fixed power scopes long ago, simply because there were so many advantages to a good variable. If the mirage gets too fugly, you can always dial them down to a lower power. But having that extra magnification available when you can take advantage of it is great. Only downside to getting into one of these really good scopes is that they'll spoil you for anything less...lol