I understand this may be purely personal preference but after running Roc/RC/EC for sometime in our server we're coming across a consistent comments that I would like to pass along. You are of course completely within your rights to entirely disregard said comments
1. Lubrication seems counter intuitive to the system. The realism element not withstanding most of our playerbase has commented that it feels like a grind mechanic that offers little in the way of engagement or teaching, to the end that most rush towards gearbox and systems that require little or no lube such as the bedrock gears, cvts etc. continually supplying and producing lubrication, especially early in rotarycraft where it is actually needed the most becomes a frustration that detracts from the learning and enjoy ability of the mod at entry level. What you do with the feedback is ultimately yours to decide but in this scenario I would probably suggest allowing for recycling of lubrication to lessen the burden, or removing the continuous lubrication requirement from some devices, or requiring lubrication for bedrock devices. The consistency is key here so it doesn't feel like a race to get out of the wood/stone/steel age just to avoid lubricant as much as possible. We have guys who's sole focus becomes rushing a bedrock breaker for that very purpose, and doing it within a day of a new world. If the ultimate goal here is to simply skip all the other models and gear boxes then it's working.
2. Multiple gear boxes to achieve ratios get in the way of
aesthetic builds. Simply put if we need 3-4 gear boxes to get the gearing right on a device while some only need 1 its suddenly changes the way we are forced to layout our base and the amount of space we must dedicate to RC machines by a great deal. It severely limits compact builds. The CVT is nice once you reach that stage (which again many of our players race to within the first couple days) but some machines require even more than 32:1. I guess here a modular gear box, perhaps a step between a CVT that would allow for more varied ratios and greater ratios would be ideal. Even if it required the same or more resources but able to reduce that gearing change into a single block instead of 5-6 would help remove the space limitations. Also on the topic of CVTs, being able to bucket in lubricant to the cvt has been highly requested, not sure if its a bug or not that you can't, but it seems to be an intended design?
3. on the topic of space saving, I love what you've done with current in Electricraft but along the same lines converting to current and suffering the loss from it yields little benefit, especially in the early game. It requires the creation of a completely new machine per device to receive power as well as the machine to convert to current. We need gear boxes to get the current right overall and then several gear boxes to get it to what we want at the receiving end. Couple that with the fact that many machines put out exactly enough power to run other machines and ANY loss means you literally can no longer use that machine for power. Again we get into a situation where EC is just avoided until end game when the loss less cabling can be used, and even then as a method to circumvent the lubrication requirements of a shaft power bus and/or for aesthetic reasons. I'm not sure there is a simple solution here that would satisfy your vision of RC, but it is a common complaint nonetheless.
4. We experience a disappearing texture issue. Fans, grinders, magnetizers, toroid magnets etc do not render when viewed from certain directions. We have taken many steps to try and solve this (Minecraft 1.6.4, with optifine, without optifine, with custom texture packs, without custom texture pack), latest version of RC/Roc/EC/DragonAPI, all variations we have tried result in the same issue. Some of these machines looks really nice and having them consistently seen would definitely add to the polish of the mod.
5. Decreased obscurity of consumption would be greatly appreciated. If the angular transducer or another device could estimate your amount of fuel/water/lubrication consumption it would definitely help the learning curve, and also go towards helping individuals feel they have mastered the machines. One instance of this was one of our players trying to get water to a solar tower, he had no idea how much it required. An accumulator wasn't enough, 4 accumulators weren't enough... he started adding in a couple pumps and finally got it right but all along he had no way of knowing his requirements to prepare for and build the infrastructure. I really like the fact that you're bringing some actual physics into play here and on that line of thinking systems design generally includes approximation of consumption of these types of things.
6. Lastly there is the issue of automation for some machines. A mode select for the way a machine is filled would be very useful. Take for instance a blast furnace. We can prefill it with gunpwder, coal and sand and keep those filled with pipes or ME export buses. If you try to dump in 9 iron to turn into steel after that, the expected behavior would be to fill the available slots first to begin processing all 9 at once. Instead it puts all 9 ingots into a stack in the first slot. Again this was probably a design decision on your part but a way to configure this would be very appreciated. Same is true for the compactor and most likely a couple other machines (fractionation machine I just fill the last couple spots with cobble to effectively block them up).
You've done amazing work on this mod, and if I sound critical it is merely because this is the short list of things we had issue with apart from all the good. I assure you the list of things we DO like would be vastly longer than this and on behalf of our players thank you for all your effort on all of your mods, keep up the great work!