Just to add to what has already been said, the concentricity issue is not a huge factor with dovetail jigs as long as you hold the router in the same orientation. Even if it is off slightly, the offset is repeated.
However, cutting something like a circle with a template, the entire shape will be off-center by that amount. In most situations, even this is not enough to be of concern, though it could in some.
I use both, Festool copy rings and P-C style bushings. It just depends in the situation. The Festool ones are nice for mating with metric sized router bits. It makes calculating the offset easier.
The beauty of the OF1400 is that pop-in style. That system is so quick and easy. I especially like it for the chip deflector when used in edge profiling, which adds dramatically to the efficiency of the dust collection.
The OF1010 has the same chip deflector, but it has to be screwed on, just like the copy rings. Four tiny slotted screws, which are comparatively a pain. The copy rings can indeed be centered perfectly, but that takes/requires some effort on the part of the user. (and an additional tool)
This falls into the category of "adjustability comes with the problem of getting out of adjustment too"
There are pluses and minuses either way. I am more likely to use the OF1010 for dovetails anyway, so I appreciate the quick-simple of the OF1400 for other tasks, where a heavier cut is more likely.
Though I would like to see a longer chip deflector available as an accessory. I sometimes use a 50mm cut-length flush trim bit, and the original one is too short for that.
