The best place to get precision collets is PreciseBits but they don't yet show them on the website. If there are enough calls asking about them they will probably add it to their list. Or at least investigate whether one they already sell will fit the DW611.
If you use anything like a split adapter insert your router will be likely to get louder from the higher run-out the insert is likely to give. Consequently, your new router's bearings will go bad relatively quickly, depending on how bad the run-out is.
CarveOne
CarveOne
http://www.carveonecncwoodcraft.com