Gday Michael
ive had a pair of spotters UNITS in BLUE MIRROR for some years now (not perscription) but i have found them too be a great pair of glasses, i use the blue mirror lens in 1m to 5m depth range for chasing big kingfish here in South Austrailia to chasing tuna in 100m out wide have had a couple other diffrent lens's but in my point of view i have found the blue mirror to be the best lens for me, they really brighten up your targeted area but also making it really clear to see by taking away the glare if that makes sense lol . Not sure weather it would differ for GT's but i would not think so. also the toughness of the glasses got me as well , for a glass lens they are pritty resilent to scratches n cracking.
the blue mirror is now called ice blue
hope this helps.
cheers Wes