sillyfly wrote:the proposed heavy-inserter is a flat improvement over normal inserters
I assumed that heavy inserter is researched after fast inserter, so the choice is fast vs heavy, which is not so clear. If you add increased resource cost for building and power cost for operations, in addition to potential flaws already discussed you can make heavy inserters viable only for mass unloading/loading from compressed belts.
I am actually fine with heavy inserters being able to only unload stuff into belts in addition to loaders for putting stuff into containers.