The worst vibrations I ever got out of my Bullet was when the gas tank bolts came loose. It took me a couple of rides to figure out what was going on as it was somewhat intermittent. But the last ride I did with it loose, the nut had completely fallen off and dropped into those little square boxes on top of the gear box. So, at least, I didn't lose it! the other problem that arose from the shaking was the tank developed a tiny leak at the back of the rear mounting plate. It didn't leak much sitting still, but who knows how much while it was shaking!
Check those tank bolts! Is your engine clanking any more with the vibration? If it still sounds the same as usual, then it sounds like something big is loose. While on the rear tank mounting bolt, the head brace that is attached to it has been known to break, too. Check your motor mount bolts, too. I don't see how the swing arm could be causing any vibration, but make sure the bolt is tight.
As for my running problems with the Guzzi, that all came from a remap I had done by one of the Guzzi Gurus. This was not a factory remap. I finally got tired of trying to straighten it out myself after jacking around with it for about 3000 miles and finally took it back to the shop and had them put the stock map back on. The bike has only spent a week in the shop waiting for an O2 sensor to be replaced. I don't know why one expired as they had been unplugged since the first remap It's been running great since then. The only real problem I ever had with it, discounting all the mapping hassles, was a broken spark spark plug cap. Parts that I've needed haven't really taken any time, except for the sensor.
As for soul and character, the bike has plenty. I get almost as much attention on it as I did on the Enfield, people wanting to know what it is and what year as with all the fancy crap removed, it looks very much like the '74. Since It will cruise at 75 or so with reasonable mileage, and it will cruise much faster at the cost of mileage, it has taken the challenge out of freeway riding that the RE offered. I've seen 115 on the speedo,which is more like 105, but it's still breaking the ton! Overall I like the bike very much and it would be a little difficult to go back to the RE with all its little foibles, and lack of power, sometimes. I've got 16,000 miles on it since May, 2013, and it's never left me stranded.
Bare
Bare