Yes. Have one.
Weighs about the same as a Sidekick LX and the device is now about the same thickness as a Sidekick 2/3. If either of those things make you feel uncomfortable, the battery isn't for you.
Shipping from Hong Kong takes forever and I have heard rumors of spotty quality control down at Mugen. There are some people around the forums that have had to return defective batteries. (My guess is that it is not a pleasant place to work and the hours are long. So, be patient.) With that said, I'm happy to report no problems so far.
After a few charges, you will start to see the benefits of the extra juice. Don't bother trying to calibrate the battery yourself, I have found that deleting the battery stat file actually makes the device expect the stock battery. All you can do is follow the instructions that come with your battery.
The extra capacity is nice and I don't mind the extra bulk. You'll have to decide if the trade off is worth it. Good luck.
Sent from my SGH-T839 using XDA App
*/ Do it again!