It always bugged me that the belt speeds increased so weird, so I really appreciate this mod, thank you! However, I noticed that common red long inserters are no longer able to pick up from turbo belts, after I added this mod to my midgame space age run (it seems to me to be the same issue the devs faced when they implemented the turbo belts iirc...) Don't know if there's something you could do about this but thought you should know :)

Just use the slower belts for slower inserters. Fast belts are not for assemblers, but for supply bus.