So, I spent a bit of time tonight messing around with overclockers, and here's what I found out.
First of all, for point of reference, a fully heated induction furnace processes a full stack of resources in approximately 42 seconds, drawing 16 EU/t during the operation, for a total energy consumption of about 13.5k EU. This is my basis of comparison, since the point of this is to determine whether or not overclockers are "worth it" over advanced machines at any point.
Now, an electric furnace running off of 4 overclockers has roughly the same draw as an induction furnace, but processes much, much slower. As in, slow enough that I didn't even bother clocking the time needed to complete a stack, it's obviously much less efficient than an induction furnace. A fifth overclocker draws more energy than an induction furnace, and still processes slower. A sixth requires a transformer upgrade, because it's now drawing 34 EU/t to operate, but has roughly the same speed as an induction furnace. It is, however, much less efficient, requiring double the energy draw of it's advanced counterpart. Adding more overclockers will trade energy efficiency for speed, and will surpass the speed of an induction furnace.
Now, it does need to be said that the induction furnace can process two stacks at once, and thus, it's efficiency is effectively doubled, meaning it only really takes about 6.75k EU to process one full stack (split it across the two slots in the induction furnace, and it takes 21 seconds to process instead of 42). However, it is limited at this, whereas you can keep putting more and more overclockers into an electric furnace.
This is where overclockers start to shine. It doesn't really show too much until you've hit your second transformer upgrade, and your 10th overclocker. This causes the machine to draw 170 EU/t, but to take only 10 seconds to process a full stack. It does cost 34k EU to do it, but you're trading 5x the energy to process twice as fast. The 11th overclocker drops the processing time to 6 seconds, but raises the energy cost to 260 EU/t...three times as fast, at 4.5x the cost. The 12th is the magic bullet, 370 EU/t, but only 3.5x to process a full stack. Six times as fast, 26k total EU consumed, only about 4x the cost in total EU, so you've hit a point where the electric furnace really shines with 12 overclockers. 13 overclockers won't even run unless you have an energy storage upgrade in it, draws 512 EU/t (plus probably some from the internal buffer), and still takes 3 seconds to process, so the 13th is a major downstep.
The true point of comparison is induction furnace vs. electric with 12 upgrades. Induction takes 21 seconds per stack processing time, 6750 EU to process, whereas electric Ux12 takes 3.5 seconds but 26k EU. I would say that, given the fact that charcoal is easy to come by and lava produces 20k EU per bucket, if you're running the equipment for long periods of constant operation, like an automated smelting line, induction is the way to go. Slower, but steady, low energy consumption for when speed isn't of the essence. If you're doing on-demand operations, electric Ux12 is definitely the way to go. Yes, you burn up more energy processing it...but you process it FAST, meaning you spend less time standing around waiting for machines to finish processing your materials, and more time using them. And time is a lot more valuable than a couple of extra pieces of charcoal worth of energy.
Now that I've taken the time to type all of this out, I really, really hope I didn't miscalculate somewhere or otherwise make a total ass of myself, lol