What I find exhausting on my 5-speed is not the vibration, but that there is no place to stretch my feet. I have well over 20k miles on mne and several 200-400 miles days.
Another down side, mine now burns a quart of oil every 200 miles an X-wedge parts are made on unobtanium.
On my more usual local runs in my old +8 oil consumption was never a problem as I usually covered no more than a max of 300 miles in a day. Many years back when heading through France for Italy from Central Scotland I had taken a pint of my usual oil with me, and stopping to fuel up I checked the oil too, though the large petrol station having loads of brands to choose from, none of which were known to me, until i spotted a can of STP oil treatment, I added that and did not require to add oil for the rest of the circa 4K mile trip...
I have read where the use of STP has been frowned upon, and have not used it after subsequent oil changes as that was the last long trip I made..but it worked for me at the time..Whether if it is still available or might be mixed with modern oils, I have no idea, Just thought to share the story.