As has been said many times, this bike is NOT an ST. Anyone trying to ride it same as they ride their ST will obviously be disappointed (duh!) since it will not respond the same as an ST at the same rpm. You cannot ride this bike and realize it's strengths by running the same rpm levels as on the ST. I would think this is glaringly obvious.
If you ride it like even a Wing or a cruiser keeping the rpm 1000 to 1500 UNDER in each gear what you would do on an ST then it will perform at peak for you. Sweet spot is really not at 62 mph (that must have been in 4th gear). At that speed, or any speed over 45-50 mph, this bike needs to be in 5th gear to find the real sweet spot (I am guessing closer to 70+ mph). Since the torque curve is flatter than the ST at lower rpm levels it will be strong up past 65 mph and way beyond, since 5th gear will take you all the way over 100 mph to the max speed (again, obviously not as fast as the ST). On this bike you should really never need to be at 4500 rpm unless in 5th gear.
If a rider cannot adjust to the riding style of a different bike than what they are used to then it is not for them, obviously. If testing it out just to know what it is, then ride it like it is intended. You wouldn't try driving a crossover SUV same as a 2014 Corvette and expect the same results? Same issue here.
I totally understand the opinions that this bike is not for many here in the ST or s-t world, but I also agree that there is a whole larger universe of riders that do not like s-t riding. I do like my ST1100, but only because there was nothing previously available that was like a GW but smaller, lighter, more nimble. The ST1100 came closer than other bikes. My opinion of the CTX1300 is that this is that bike (smaller, lighter, more nimble than the GW but just as comfortable for LD riding and touring and plenty fast enough for that kind of riding).
I tested the ST1300 and it was just too short in wheel base for me. That made it too "twitchy" to me (meaning too willing to lean into a turn, even when I wasn't looking to do that). That does make it more nimble, but for me it was too nimble. Like a kid with ADHD who has a hard time running in a straight line. Good for twisties. I do like curves, but I prefer touring. I've always felt my ST1100 was better (for me) than the ST1300.
Oh, and as far as engine heat... I've always felt my ST and especially the ST1300 heat was worse because the engine was enclosed so much in plastic. That would tend to hold more heat in and make both feel hotter on the legs. With an open engine there should be a lot less heat to the point where it may not even be noticeable. (remembering my year with a Vulcan v-twin - open engine= no problem with heat, especially when moving).