right now, the replicating basic transport belt, from bob's logistics, requires basic transport belt, and basic electronic unit, could you change this last one for the basic circuit unit?, you have that one from the start, however you dont have the basic electric unit until way later on the research tree, and by then you already have the transport belt (yellow one), so in order to make the basic one useful it should be craftable from the start, and for that to happen it must have the basic circuit unit, and not the basic electronic unit

and same thing for bigger tiers, shouldn't faster replicating belts be more expensive?, like fast transport belt require electronic circuits unit (red one), express require logic (blue one), and if bob's mods present, the last two belts requiere the purple, or the blue unit (depending on whether bob's electronics is installed)

That makes sense, though I'm leaning away from having the recipes at all, at least by default - one of the more recent releases makes it so you can shift-click belts to grab a ghost replicating belt, making the functionality much more similar to the ghost rail planner and removing the material penalty for using what's effectively a slightly-smarter blueprint. So I'm thinking having items at all is going to become a default-disabled option, or potentially be removed completely - I'm curious about thoughts on this?

what do you mean habing ítems?, I' talking about the recipes