Back a few years ago, I bought both an XF10 and a GR I. Even back then, the XF10 was more prone to hunting, and overall, similarly slow to focus. So instead, I used their snap focus feature kind of a lot. But the GR implementation was miles better: just full-press the shutter in any mode. No need to fiddle with a dial first, no need to change into snap mode. For a mode designed for speedy, spontaneous capture, that was crucial for me. The other thing was that the GR turned on really, really fast. I'd pull it out of my pocket, switch it on while I raised it, and immediately full-press the shutter. It would take a picture before anybody could react, pure magic. The XF10, in contrast, is somewhat slow to switch on, and then somewhat slow to react to anything. Not terribly so, but it's just not a very snappy camera.
So I sold the XF10, and kept the GR, which served me extremely well for a couple of years.
Eventually, I replaced the GR with a GR III. Its autofocus is actually fast enough that I don't use snap focus much any more, even though it's still "slow" by modern standards. Besides, the higher megapixel count makes zone focusing inaccuracies more obvious. The bigger boon here is the GR III's IBIS, though. That's just tremendously useful in this light a camera, that's often held at arm's length.
That said, the GR III is a $1000 camera, while the XF10 and original GR were $500, and can nowadays be had for very little money on the used market. The X70 I have never used, but the flip screen does sound appealing. It has become a bit of a collector's item, however, and prices have grown way beyond reason.