This is a good thing. It doesn't actually nerf the Mining Well, only puts it in the same ballpark as the quarry. They can still be used in frame mining machines just as well as they had been before, it will only require more power - the same amount of power as a fully powered quarry, only it will work faster.
It is now balanced, instead of overpowered in comparison.
How the heck do you figure it's balanced? The quarry is orders of magnitude cheaper and easier to build than the Mining well frame machine (Did you read my post that included what goes into one??). Quarries are cheaper and easier to run. If you only used ONE Mining well to make a functional machine, or more accurately, if the 16 well frame machine only drew 60MJ/t total to run at full speed, I could see your point..... but to make a machine that functions at a worthwhile level, you need SIXTEEN of them.... plus a LOT of other materials.... and then to top it off, if you want it to be able to run at full speed, you have to supply over 400MJ/t (and that's assuming you've turned down the loss rate for the tesseracts like I have.... figure 500-550MJ/t at the default 25% loss level). Unless you have Power Converters and a fusion reactor or a bunch of Ultimate Hybrid Solar Panels, making that much power (about 1.2kEU/t) is very difficult and costly - Even with those high tier power generators it's VERY costly - So if you cannot supply the 400+MJ/t it needs constantly, you will have to run it until whatever energy cells you have on it are empty, then wait for them to recharge before you restart, which depending on what you're using to make MJ, could take a while (I started with about 14 upgraded electrical engines that struggled to make 100MJ/t). So in reality, the way it is now, in 1.4.7, actually is more balanced. It already requires about 7 times more power than a quarry to function at full speed. Possibly really close to 7 times faster. And it costs a TON more just to make. An hour or so punching rocks and trees and you could have a quarry... You need to have run quarries to get enough materials to make the mining well frame machine.
Of course, as I said earlier, if Redpower goes away, it's all a moot point, but that's not the point...