Is there a big difference in value when comparing the different generations of Juliet's? I have a pair of 3rd gen plasma/fire Juliet's, and replaced the lenses with new ruby when they were sent in for a tune up. All my glasses I wear, none are collected for viewing, and value doesn't really make a difference to me, but I am curious. Are the third gen more valuable than something newer? Would it be wise to replace the lenses with some fire lenses, and wear these less often? I doubt I would do that, but just wondering.