Last year I purchased an iFlash Solo and 4th Gen iPod Converter for my 20GB 4th Gen iPod. (They now have an iFlash with the converter built-in, but at the time I bought my kit it wasn't available.) In October I finally got around to installing it, and it works great!
I used a 128GB SanDisk Ultra SDXC UHS-1 Class 10 card that's rated for 80MB/s. I figured a faster one wouldn't be too advantageous, as the iPod only has an ATA-66 bus. I didn't format the card or anything, figuring that would be done by iTunes during setup.
Overall, the device is pretty snappy. Startup and wake up are significantly faster, and the iPod is noticeably lighter. Everything seems to be working just fine, and I'm pretty happy with it! Not bad for a $40 kit! I would definitely recommend it for anyone looking to spruce up their dusty old iPod.
By far the hardest part was just getting the iPod open in the first place! I only had a crappy spudger with me as part of my travel kit (yes, I travel with a spudger) and it took me around 30 minutes just to free the front face.
Make sure the "Hold" switch is in the lock position, indicated by an orange colour. Starting at the top of the device, work the spudger in and around the corners, down the sides. There's five tabs on the left and five on the right which must be pushed in to release.
Be careful, though, because there's a data cable still connected to a little board that has the headphone jack and lock switch. So just open it like a book and there you go!
2
Removing the hard drive
After disconnecting the data cable, the next step was pulling out the hard drive. I used the spudger to gently push against the plug, being careful to not stress the ribbon.
3
Preparing and installing the iPod 4G Converter
The next step was to prepare the iPod 4G Converter, which is a rigid ribbon cable and plug that you have to bend in two spots. I was a little wary about bending it too hard and breaking something, but it ended up being okay. In this shot you can also see the crappy spudger I used during this project.