I think we should be able to either filter hoppers, or change the hopper speeds. This would make it so autocraft chests are actually useful. As it is, if you try to make a IG farm with an autocraft chest, the items leave the chest quicker than they can be crafted into blocks.
The filtering option, which I think would be easiest and best, would just allow the player to filter iron blocks. This would ultimately remedy the situation.
Hoppers can be filtered through hopper filters (hopper filters is not a manacube feature rather a technique used in redstone). You can find many tutorials on how to build one on youtube.
Personally I don't think adding the ability of increasing the speed of hoppers is going to be beneficial (server side). Firstly, the item packets would need to be updated more quicker resulting in possible server lag. Secondly, there are few to non plugins that support your idea. The manacube admins could code a plugin for your idea but I am almost certain they will not have the time to code a whole new plugin for such feature.
To sum up, your idea is a great idea although it comes with it's trouble. I personally would love a feature like this (for survival cause I play survival heh) but I am afraid that it won't be beneficial to the server as it will only make it struggle more.
**Some of these statements may not be completely true, if you want a more professional review to your idea and it's disadvantages please contact a manacube administrator or look up for advanced hopper lore on the internet.**