It gets me every single time

You have given me much food for thought. My 82 750 Maxim has those stock adjustable bars, I may have to experiment. I have been having too much fun riding to be tinkering but winter is fast approaching.

 

And (pardon my ignorance) what is a Bar Snake?

 

They slide inside (regular tubular bars) or are poured inside your bars and take up all that empty space and press against the metal to minimize vibrations-its a polymer and weighs very little. I have never tried one, but I have a buddy from Florida that says it smoothed out the higher rpms on his 900.

http://www.barsnake.com/

The whole deal with handlebars is what suits your riding style and a little to do with your frame. I'm average height 5'9" but I have broad shoulders so the stock bars don't feel right. Plus I like to have maximum control over the load when I'm cornering and sport style bars allow me to use all my arm strength and don't require as much grip from my hands.

I have no idea how those custom guys maneuver their bikes with those arms above your shoulders bars! Seems like you would get tired easily.

Since you liked your friends CB900ss you could try and find bars that would position you in a similar way. Best to take measurements while sitting on the Honda then figure out what you'll need to make that happen on your XJ. When buying bars there are three dimensions that determine your grip location: width (tip to tip), rise (from clamps), and pullback from center.

One thing to consider is if the changes from what you have now are significant you might need new cables or reroute the ones you have. Primarily brake and clutch are the ones you have to worry about.

 

To add to what Merc said, I used steel shot (smallest available) from a gun shop, seal one end and just fill up the bars from the other end, then seal it and you're done.
Adds more weight than the polymer stuff and can be taken out if you don't like it.
2 cents.