Ah, I stand corrected. Also, obviously prores and DNX are intermediate codecs, not delivery compression specs, but there are lower bitrate options if need smaller sizes.
But it seems the issue in the article is with one component of AME - the mainconcept h264 encoder - not AME as a whole, which I find quite speedy.
My personal preference for high quality encoding / transcoding of all kinds is actually a bit of an oddball, a $30 consumer app called "Aiseesoft total video converter platinum"
My guess is they are in a legal gray area in terms of being able to rip and convert MTS / MXF, AC3 .VOB files, and .ogg / .mkv and more to ipad specs, but it also supports CUDA encoding and uses x264 under the hood (along with any other installed codecs). It was literally the only program I have ever found able to reliably rip .mkv streams back into an editable format