Specifically a SRAM X.4 replacing an older (2004?) Sora one. My assumption is that the mountain bike derailleurs would be able to handle a higher stress, such as those exerted in sprints. But a few questions, 1) Would I even see an improvement going from my current to the new? 2) Are Shimano Sora shifters even compatible with this derailleur? 3) Would it even be worth it?

I know it's a bit of a stupid upgrade, but the derailleur are only $25, so figure it might be a way to upgrade a little...