If you talking about the 55mm version, then yes. I have used it side by side with my 65mm swaro sts. The kowa is a great light weight option if you counting ounces. I think it gives up a little bit to my STS in clarity to my STS especially on the upper end of the magnification range. Same with light gathering. That said for what it is and what it weights its great piece of glass. I cant see anything coming close at that weight. depending on what and where your using it I think its good addition.
I went with a TSN-553 after reading tons about them. I haven't got to put a lot of time behind it yet, but it doesn't disappoint. I upgraded from the Vortex 55mm and it was quite the upgrade. S&S archery did a few blog posts about it comparing it to 65's and it held its own even being smaller. The glass, weight, and quality for the price is what sold me on it. The larger glass will outperform, but its also heavier. I just need it to verify an animal is worth pursuing, not worried about counting inches at this point.