Quality in Efficiency Modules interferes with already existing designs where efficiency modules are employed to reduce power consumption. Addition of quality to regular efficiency modules would result in efficiency-utilizing machines suddenly producing quality products, which would clog entire bases, making this mod impossible to integrate with an already existing run.

With this mod, you effectively get quality modules you can put inside beacons, without a speed penalty, which can be stacked with productivity, and on top of all that, used to make uber-quality setups with beacon spam.
The mod's idea is good, I personally like it, but its implications are far-reaching, just like "vanilla" quality (to remind you, 25% productivity bonus in a single module is insanity).

As for my idea: Efficiency modules should not be touched. This mod should add dedicated efficiency-quality modules which provide a much less quality and efficiency benefit, however they should retain the ability to be used within beacons. This way, they can't be used as quality modules without the speed penalty, but work as a counter to speed modules, as per the mod's original intent.

You raise some good points. The quality of the efficiency modules doesn't get as high as a straight up quality module and the value can be reduced further. And you could only get 12-16 beacons around a machine (in vanilla) so I don't think it would be much of an issue until you start using the higher quality beacons.

The way I had imagined the use case if this mod was in conjunction with my other mod which has addition quality tiers and to get to them the odds are greatly reduced.

Also I quite like the idea of the challenges this extra things to think about and how you may would have to think how much extra speed do I have to add to prevent varying quality but I guess that's just me being a glutton for punishment and I think many others would be to.

I will add an option in the mod settings to add a specific quality-efficiency hybrid module and leave the regular module along because I quite like the idea. Any suggestions for the colour of this new module as it was your idea? :D

I'm quite flattered, thank you! I didn't check out your other mod closely, it's interesting you made your higher qualities have less of a chance of being rolled. I don't think I saw other mods do this yet.

As for the combined modules, I was thinking combining the greenish hues of efficiency with the sharp red lights of quality refinement could work, but if it comes out ugly you can just make it some variation of light green or lime :D

Well I will give it a go at the weekend. Busy couple of days with Christmas approaching and work commitment.

As for the odds of getting the higher tiers being reduced each tier I've only saw it referenced in one other mod but the odds were the same for every tier after legendary which didn't feel quite right to me and made it seem too easy. I do also have another mod planned that changes the way qualities are unlocked in general but that's quite a way off yet.

Anyway back to the colours of the new module I was thinking something similar to what you said because it just makes sense. I also need to decide on the recipe for this new module. I was thinking like the hybrid modules "bob modules" (completely different bob) how you can make the hybrid modules in many different ways and because of that how is the recycling recipe going to work. Adding to this its balancing that with the productivity bonus of the new space age machine.

Anyway that's very much a problem for me to figure out :'(
I'll post here again once I've made the changes.

@Grand_Teki proving a little more fiddley than I had expected but I am working on it. Just need to work on the alternate recipes and fiddle with the images.