I sold my 2005 Gen1 FJR this spring to reduce the stable before getting the S10. Great bike and a friend is riding the wheels off it now.
The S10 will easily do the same missions as an FJR, but quite differently. Ergos of the S10 actually seem superior to me: more upright/neutral/less-committed riding position, wider handlebars, a LOT more legroom (one of the weaknesses of the FJR). But there is definitely less weather protection, you don't have the electric windshield to match up to the weather, and the S10's engine will seem agricultural and gutless compared to the turbine in the FJR. That doesn't mean it won't get you down the road just fine, but there is a big difference between a 90-hp twin and a 125-hp four-cyl, especially if you like the very high-speed stuff. The FJR is like a Corvette; the S10 is like a Range Rover. For absolutely pure pavement, I'd rather be on the FJR, but for very tight pavement and, of course, any gravel or dirt, the S10 will handle it in stride.
I'm a minority on this forum in thinking that the GS is a slightly better bike overall compared to the S10. It's significantly lighter, makes a little more power, has better sorted factory accessories, and I'm a fan of the telelever front end which gives wonderful stability and does a better job of separating steering and braking. But..... the S10 is clearly a better value and there are nagging aspects of BMW ownership that I wanted to avoid, like the fragile and difficult-to-service clutch/final-drive system of the BMW, clunky ABS system, and general lower-reliability overall. Having said all this, the GS is a great bike and is serving an awful lot of people very well.
If I was in the market right now but didn't need to move right away, I'd stay on the sidelines until the new 1200 Triumph hits the market next year and we get a read on what the wasser-boxer is going to be. There's also the big new Honda to think about. Both this new Triumph and the Honda will be closer to a FJR than a S10/GS, so if you wanted to tilt more towards smooth, big-horsepower, multi-cyl characteristics but have a little more suitability for gravel than a pure road bike, they'd probably be good choices.
- Mark