I have a 50, 80, 150 kit. I also had a 250CT which I sold to replace with a 250CF, just haven't found one yet. I find the 135 vs 6x6 analogy doesn't always work, the 80 is my most used lens and can be both wide and like a 50mm (in 135) at the same time. It has to do with each particular shot and how the square vs rectangular format looks. I would not like to have a 60 instead of a 80 for a normal lens as that would then make it always look wide, the 80 is my most used lens.

If you do want to try swapping the 80 for a 60 then buy the 60 and use it side by side with the 80 for a while, don't sell the 80 to buy a 60 and then find it doesn't suit you.

As for C/CT vs CF, the focusing can be just as heavy with a CF lens, it is more about the rest of the ergonomics. I think either a C, CT or CF lens is probably going to benefit from a service and regrease of the focus mechanism as that is probably going to make a difference. My 80mm is the newer CB type and the focusing is much much lighter. My 50 is a CF and it is heavy. My 150 is a CT and it is in between. The 250CT I had was very heavy to focus. So I'm kind of thinking of sending everything for a service and relubrication to make sure they are all ok...

To give you an idea of what I use most:

In my 135 system I use a 50mm and 35mm pretty much split between the two and on occasions a 135mm.

With the Hasselblad the vast majority of shots is taken with the 80mm. The 250mm is the next most used for general shooting, the 150 is for portraits and the 50 is my least used lens. Although I wouldn't sell the 50 as when I need it I need it.