G'Day Mate, well most 69-76 K owners were disappointed with the 77/78 redesign, most comments I've heard were more about it's "bloated" appearance, than it's "sleek" lines. Kinda like Elvis in his last couple of years.
I don't know that they're any more reliable either, they are all very reliable, but it's universally accepted that the late model engines were the best built, as Honda continually fixed any problems with them as the engine evolved over it's 9 year life.
Still, it's a Honda 750, so it's still a wonderful motorcycle. Hows that R5 going? Geez, I remember when I was just 14 years old, sitting on the back of my mate's R5, I peeked over his shoulder and we were doing 105 Mph, it was summer and we were just wearing sorts and T shirts, those were the days! Great bike though, I wish I had one now. Cheers, Terry.