Wow...what a hard to answer question, based on the variables.
The 'zook will definitely outhandle the FJR heads-up, corner for corner, but SOOO much is dependent on the driver.
This past weekend I spent a couple of hours chasing some VERY fast hooligans through the Ocala National Forest on a group ZRX Owner's Association get together.
Just for fun (and thrills and deathwish) I went with the 'A' group for a ride when I got a little bored with the pace of the 'B' group. I was on my FJR. The rest of the pack consisted of heavily modified ZRXs, a few stock ZRXs, a new, unbroken-in Gixxer 1000, a new Triumph Speed Triple, a new Triumph 900 Thruxton and a CBR1000R.
Out of that whole bunch, me and the Feejer were sixth in line hauling ASS through the forest. 30mph turns became 90mph sweepers. And boy, did I have to muscle that 600+ pounds through those turns. But some would say I'm a bit squidly, too, but I kept the pace-setters in sight. My chicken-stripes are totally gone, but lemme tell ya...touching down a peg at 90mph on a bike this big and top heavy is a puckermaker. Fun, though, to look in your mirrors and see a Gixxer1000, CBR1000 and Speed Triple BEHIND YOU!
It was also very gratifying to show a bunch of fellow ZRXers how competent the FJR is. Faster, too, on top, I believe. That tupperware does help the beast slip through the air better than the barn door known as a ZRX.