My two cents.
Harley Davidson make mediocre motorcycles with lousy frames but package it all into such a beautiful looking (and sounding) item it sells like hotcakes.
I don't know about Sportsters, but Dyna and Touring bikes all share the same design fault: the rear fork is hinged not on the frame but on the gearbox.
Yep !
They only had to buy a 1950's brit bike and copy the frame, but no, they had to go their own way
and improve a 1920's design to the point you just can't improve it any more... and this is what you get.
Death wobble.
Look at the three Youtube videos posted a while up the thread.
Ask yourselves... would you buy a car whose rear axle was not bolted to the chassis but to ... whatever else ?
BTW My other bike is a Dyna...