"Can someone with gt3 seats comment on their comfort level in regards to long drives? Especially for us 40's guys with sensitive backs."
I got a set of OEM GT3 seats and when I first installed them they seemed to be the same height as the factory seats. I have a long waist and so sit a little too tall in the saddle with factory seats. I got the Brey Kraus brackets for the GT3 seats which are perfect, drops the seats a little and are setup at just the right angle of tilt for me.
GT3 seats for long rides are great for me, at least as good as factory seats. I have done several 3-4 hour drives no problem. I would think they would do well for longer drives as well. Only problem I have found with GT3 seats is that they are a pain to get into and out of. For me, I have slide the seats all the way back to get in or out of the car. They are also a bother to look behind you for backing up because of their width at the top. But I still think they are great.
Ed