Everyone loves this mod on my server. I hope when you do the upgrade slots you will consider not being so taxing like another mod on these forums. I enjoy charging faster but not at the loss of to much power or its not fun
Currently, the pads use up a minimal amount based on tier, just to run. They'll increase usage along the same line, for each oveclocking module that you insert, but the main "power sink" will be the fact that they're able to charge up so much more power at once. It's not linear but it's not insane, either, for the following reason: a lower tier pad will never quite match the next tier above, even with maxed out overclockers... you'll always need to upgrade to the next tier to get that amount of charge-power (not to mention that the O/C upgrades won't help you charge a higher-tier item in a lower-tier pad).
Additionally, the pads will accept transformer upgrades to accept power from higher tier inputs, and storage upgrade modules to increase how much EU they can hold at any one time (the higher tier pads can accept proportionally more compared to the lower ones, making it significantly more useful to upgrade a higher pad than lower one - the electronics of the lower pads just can't handle too much!) -- and it encourages upgrading.
Then there's the drain module... which has the UI complete but no functionality... yet! Not quite managed to balance it the way I want it.
Regardless, it'll be a bit before it's released, I'm afraid, as I'm currently having some pretty serious issues with entity sync, using the IC2 API (it just isn't up to the task, given the GUI changes)... so I'm having to do it the hard way and the learning process for packet handling is nothing if not steep. :\
In short: Soon™