I'm 5'8" and weigh 145 pounds so I'm not a big guy...
Not to bash anyone's opinions but I listened to guys for years talking about how, "A sport bike is a track bike and uncomfortable for street" crap all my life. I stayed away from them because of this or the " It's too much power but for race guys" crap.
I road all kinds of bikes and spent a lot of money on them to try and get them to be what I really wanted. A sport bike.
I can honestly say, My GSXR 1000 is the bike I have been looking for all my life.
It is powerful, handles, looks, sound. I am actually more comfortable on it myself than I was on the FJR. The windshield is just enough so the wind isn't trying to blast me off the back but I still know I am on a bike.
I know guys that ride 3-4 hours to the beach every weekend on them.
I say do it. You are a small guy and even more perfect for these. They were made with small guys in mind.
Do it now before time runs out. I don't regret my purchase for one second and for once in my life I am not thinking about my "next" bike anymore.
If you want an addition to the FJR which is most likely your tour bike, to work bike, carry things bike, camping bike, whatever bike. You want a pure sport bike to do curves on get a 600 or gsxr 750. I would also say take it to the track. The FJR will do everything you need a bike to do safely on the back roads. You aren't going to get much more safely out of a pure sport bike.
Take some track classes, get on the track and do the turns there. You will never get as fast on the street as you will the track. Plus the insurance for a 600-750 will be easier than a 1000 bike.
Track Lesson School
This is where I am going soon. Most tracks require some type of training before being able to get on their track. After this I will be licensed to do it. Most tracks have leather rentals but I have a pair I just bought.
Short of removing radiator fluid and putting in some type of substitute (many exist) some tracks have other specific requirements such as wiring oil plugs, brakes, etc.
Once it is done you can have a blast...
Any 600-750 you should be able to find 3-4 grand and is perfect for the track.
Go for it... Street carving kills...