It just makes it more center-heavy so-to-speak. That can be really nice with some lenses. One of my lenses looks like crap with normal photography, but when it is on some extension tubes everything becomes much better. Part of that is from aperture calculations too.>>3599077>$90 for each tube
Yeah, I'd certainly shopping around for a 3rd party tube set with AF. Whatever you get, make sure it is all metal mounting flanges. The cheap as shit plastic ones tend to start breaking little bits off until the lens falls off.
I'm not familiar with Fuji gear, but if the aperture is all electronic then you can DIY your own tubes, if you have the skills and tools. I did that with one of my tubes for general information and AF, but not aperture setting since that requires a linkage arm.