Depending on what Sightrons you have, the Delta is close to the SIII in clarity.All this info helps because money will be spent.
Right now I have several Sightrons. I had Leupolds and was going to buy another Leupold when I got into midrange but they don't offer the 42x in a reticle that Works, and can't get them to change reticle s anymore so I went with the Sightrons.
So having two Sightrons,they are good, but Iv looked through some 3k glass at a few places and yes, ther are much better ways to see long range than what I have. I'm not selling my Sightrons. They doing my bench stuff.
The delta has got my curiosity up
Since you mentioned kestros, I'm seriously debating on getting a Kestros. But sometime while back I was debating someone on here about the use of one for short range bench rest. Not so much a debate but they adamantly was against it.There is only 2 options if you already have Sightrons and want to step up. The old standby NF Comp
and the Sightron SVSSED ....but with the SVSSED you will need a lighter rifle for the extra weight at
40 plus oz's.. I used a Panda Action in my Kestros for the boat anchor. Just my 2c YMMV as always.
( Within this price range that is )