Mill options for oily seeds plus grains?

I like to add a bit of flax for fiber and omega-3s in many of my recipes, and have found that my Kitchenetics impact mill can take no more than 5% flax before it starts to gum up unhappily.  I recently bought a MockMill and it, too, recommends no oily seeds (although again a few percent of the mix being flax dilutes the clumpiness of the oily seeds and causes no trouble). 

The only mill I see advertised as OK for oily seeds is the Wondermill.  I've got one and it will grind oily seeds but I find it difficult to get the fineness of flour that allows the seeds to slip into recipes without as much textural impact from the coarser grind (although of course there is always the issue of the thickening power of the seeds to take into account).  Are there any other options for an electric mill that will grind flax seeds very fine?