I took the camera out yesterday on the way home from work, put the XC 50-230 on it, and camped out next to one of the bike lanes in Harvard Square to try out the tracking focusing. It wasn't a good experience. I put the camera into Wide / Tracking, put the front focusing dial into AFC, and aimed at bikes coming towards me a block away.
KBRX6444 by
gordopuggy, on Flickr
About half the time, the first shot was fine, but in all 5 runs I did, the camera lost the bike very quickly and stayed focused back near the starting point. I saw the little boxes appearing and squiggling around, but they weren't really grouped tightly around the actual moving subject. And there were moving cars behind the bikes, which makes me think that was the issue...
KBRX6472 by
gordopuggy, on Flickr
In frustration, I put it back into AFS and Single Point, moved the point over a click, and did the "full press" trick, and was easily (EASILY) able to nit pick out perfectly focused shots of a moving object narrowly visible between closer objects...
KBRX6500 by
gordopuggy, on Flickr
So I have some homework to do before I figure out how this feature will help me.