100% sure the 66 doesn’t have the same glass, even the 77 doesn’t have the pure fluorite crystal glass. According to S&S archery, the 55mm is just edged out by the ATX/STX 65mm Swaro.
Now I have not used the ATX/STX but I have a Kowa 55mm and after having it a short period was confident enough after having a Swaro ATS 80 HD with both 25-50 and 20-60 eyepieces that I would keep the Kowa and sell the Swaro.
The 66 Kowa will weigh more, is bulkier and sorry but the pure fluorite crystal glass in the 55mm will be better, it just is. But yes everyone’s eyes are different, I’ve heard many people say the Vortex Razor compares well to Swaro, not in my experience but people say it.