I have a new (Feb 20) non XT version. The only vibrations I notice are around 5500rpm, especially in 3rd, or 4th gear. This is only when I’ve changed down and I’m pre over take or similar. ( so sitting in that rev range on light throttle, before adding throttle to overtake).
Cruising at that rpm there is a slight ‘rough’ spot, but in both cases hardly detectable.
My bike is now at around 900 miles, with the first service out of the way. So I’m using full rpm.
As v twins go, the DL650 motor is pretty much the smoothest I’ve ridden.
I don’t have Suzuki engine bars fitted. I have Heed ones, which I fitted myself, with no difference in ‘feeling’ once fitted. (They were done at around 200 miles).
In terms of the seat, I opted to lower my bike with different dog bones. I found the stock seat was hard for the first 200-400 miles, then seemed to improve. (I was lent a zero mile DL650 while mine was serviced at almost 700 miles, and the seat on the new bike felt very hard, so they do give).
I think as others have said, it’s time to discuss with the dealer. If they have another one, a demo or something they could perhaps let you try that.