The short answer is that you need to take a test ride and see if the GT will work for you. But bring your checkbook because you will buy one.
Passenger comfort isn't up to the LT. But adding a trunk makes it acceptable, especially if your "friends" haven't ridden on an LT to compare it to.
Saving 200 lbs makes a huge difference, especially in low speed situations. The extra grunt sure doesn't hurt, either. And the GT is a plenty comfortable all-day bike, if you get it set up right for you.
Weather protection isn't quite as good. I added an Aeroflow windshield and their AeroGards which gets the extra wind off my arms. Some guys leave it alone, or add a Cee Bailey, CalSci, or Z-Stream windshield.
I got a custom seat the first day I brought the bike home. I do a lot of miles so it was worth it to me. Some guys are fine with the stock seat, but like with the LT, some just aren't. There are a couple of bolt-on options (Sargent, Corbin) but a proper custom saddle makes will always beat them. I've been happy with Rocky Mayer's work, but Russell also makes good seats, especially for larger riders. Or you could go with Rick Mayer, Rich's, etc. And I know that Bakup makes a driver's backrest, because they used my bike for the pattern.
There is a large 49L and a small 28L trunk available (same parts as for the RT). The 49L trunk comes in any color you like, as long as it's silver.
A few guys have have them color-matched with good results. It pops on and off in seconds with the key. There is no power to the trunk so no brake light, but something could be rigged up if you really wanted it. You could also go with a Givi trunk with an adapter plate which will save a few $$, but I don't like the look as much.
The bars have 5 height positions, over a 36mm (1.4") range. Changing them require loosening two torx screws and sliding the bars up or down. Some guys go full up, some full down, some in the middle. And some of us added risers to get 25mm (1") back and add another 25mm (1") height.
There are several peg extenders available (Verholen, Suburban Machinery). Withe the factory seat in the high position and peg extenders, there is more leg room than on an LT, although your feet are further back under you. But aggressive riding will cause the extended pegs to touch down easier.
As for the biggest adjustment from the LT to the GT, that would have to be throttle control. Not that the GT is difficult, but a slight roll-on will have you into triple-digits very rapidly.
My radar detector has paid for itself many times over.
Lie I said, you really gotta ride one for yourself.