I have the have the buck horn style bars on two of my bikes. One an 80 Honda CM400 The other an 81 XS650. On the XS I cut the bars off. Half way between the lower and upper bend. Plug welded them back on at a more comfortable angle. This made them too wide so I cut two inches off each end.
They are now more of a mid ape bars. Much more comfortable. Now my arms arm straighter, not having my elbows tucked into my sides.
I agree a small light bike is more tiring to ride long distances. The first summer I had my '03 Harley I did 2100 miles in three days. Tiring yes, but not near as tired as I would have been riding either of my XS's. The extra 300 lbs. keeps the wind from blowing you around.
Leo