Upload & Sell: On
If you're not limited by the resolution of the X100... don't change!
1. The 100s is a bump in resolution, but not a doubling as measured in mp. I'd guess the next round brings us 20+, a much bigger jump.
2. The 100s has an XTrans sensor. Great for low-light. Not so great for landscapes. RAW developers are still figuring it out (though I really, really like Aperture's take). I expect incremental improvements from current RAW developers-- and perhaps bigger improvements in future XTrans generations.
3. If it ain't broke, don't fix it. This is a bad time to sell an X100 (the X100s has pushed the price low) and a bad time to upgrade to the 100s (it's currently the best XTrans sensor version on the market until the X-E/X-Pro get upgraded themselves) because it's selling at a premium.