My point is simple
Your looking for a list of people here that have been dissatisfied with one or the other grapple and with only 4 folks talking about having experience with more than one size out of how many? Shows just how unrealistic your asking is! Most here wouldn't have enough time or money to entertain which they prefer because most jobs could be done with any grapple and if you have never had the use of anything else you have nothing to compare it with.
I will not entertain you with my exact use, its more fun letting you guess but I will tell you that I get done much quicker with the 72 and have less wasted time fighting for a good load than I ever did with my smaller grapple. I also get more into the bucket and keep it there with the dual lid than I ever did with the single and its even less time spent fighting for a good load at the pile.
I am glad however that you know my needs better than I do and will send you a PM the next time I think about buying something for any of my tractors. Maybe this weekend you can tell me which size grapple I will need for my intended use Choices are 72", 55" or a 28'custom for the backhoe the others are a bit too hard to dig out of the old barn right now.
The best for me is justified the same as the best for you is justified but nothing is justified for everyone else no matter how eloquent your wording is until they have had the experience with different grapples!