living under the same limitations of choice of the Southern Hemisphere (compared to our North American friends), here is my take:
1. unless the bearing is a complete dud, the concentricity of bearing and bit is a given; the centering of the bushing, not so much. The so-called universal base plates seem to be less than universal.
2. It is possible to use a bearing/bit combination on a PC type of dovetail jig; similar caveats will apply as for a bushing:
- make sure that the bearing OD fits between the template fingers;
-the correct depth of the bit does not locate the bearing above (disastrous for the template) or below the fingers (disastrous for your workpiece);
-the bit has the correct length and dovetail angle recommended for the jig;
3. Whatever you do, do not lift the router off the jig while the bit is spinning.
4. Since you have not purchased a jig yet, if Milescraft sell in Oz, i would recommend you look at their dovetail template-making master-jig. It allows you to make your own jigs, of whatever size you want, in two styles: PC style, and also Katy-style, such a Tom is using on his router table, above. You will need a straight bit, a dovetail bit, and their bearings. A centre-finding ruler will speed things up, but is not essential. Since the jigs are made of MDF, if you forget not to lift off with a spiining bit, worst case you have messed up some MDF. Also good for box-joints.
That Ryobi is a nice-looking bit of kit -has not been released here yet. I have had two of the predecessor 1600RE - only problem I had was bit slippage with 1/4in. shafts.