I needed some Keller-compatible router bits for thinner stock, and found a set of bits on eBay. I had seen bits from this seller before, they're yellow and the selection and prices are good.
The feedback looked generally positive, so I figured I'd take a chance.
When the bits arrived I found that one of the straight bits (the one I really wanted to use) had a shaft that was well over 1/2" shorter than the others. The shaft was too short to fully engage the collet.
So I figured I'd do a little checking with my calipers and found that the cutting diameters of the straight bits was greater than the diameter of the bearings. While the bearings were the .625" you'd expect, one bit's cutting diameter was .627" and the other was .628". So these bits, if used with the Keller jig, would actually cut into the jig itself. BTW, the cutting diameter of the original Keller-supplied bit was .620".
When I went to return them I noticed that the seller had over 22 revised feedbacks. When I left negative feedback and a comment that the bits will damage the jig, he E-Mailed me an offer to refund my shipping fees if I revised the feedback. When I declined, he started the insults.
Nonetheless, a template bit should probably never cut wider than the pilot.
My advice would be to avoid these bits. If you are going to try them, make sure you check the bits before you use them to avoid damaging your expensive jigs.
I actually found some bits from Amana that are priced right and on the way. I've had good luck with Amana stuff.