My personal experience is with narrow HP 406 & 451 tyres and NO suspension on the bike.

I've ridden centuries, (miles and metric), multi day tour, fast group riding and general commuting....didn't think I needed suspension, didn't suffer from harshness...... and I've broken my back/spine twice.

Maybe I have my bike set up right?

It will be interesting to see how my opinion might change when I restore my F frame Moulton.