there might have been a batch of ring kits that were out of round, see this thread
the main benefit of the linkage kit is that one could easily attach motors to them and use a wound spring to keep the excess chain from getting in the way. this would make a very compact portable setup more like the shaper origin in size. it could be boxed up shipped as a turn key setup pre assembled. the linkages also have better torque.
thousands of maslow kits have been sold, but many never built collecting dust. It’s a small percentage of users that advance the kit to be better.