I have no idea why people mess around with the newmodeus adapters hanging on with only one screw. If you do a quick ebay search you can find models actually suited for the uMBP's with the 3 mounting screws. I have the smk312 adapter sitting in my 2010 13" MBP and it works flawlessly. And to boot, they're $10-20 cheaper than the newmodeus.
Here's a link to the adapter I'm talking about, free shipping to most places in the world, I think UK is $3 extra:
http://cgi.ebay.com/2nd-HDD-caddy-A...e_Internal&hash=item3365de6c62#ht_3386wt_1135
Why mess with the crappy newmodeus adapters? Just cause they are more expensive doesn't mean they will fit better or are better quality. From the pictures they look identical. Same goes for the MCE adapter. Someone on the previous page bought one for 128 euros and that adapter looks identical to the one I paid $25 for, it just comes with a CD of instructions that are online, a phillips screwdriver, and a crappy enclosure that needs 2 USB ports.
I bought the $25 IDENTICAL adapter, then spent another $30 on a used macbook air external superdrive, bought an unlocked USB to SATA adapter for $6, popped open the external superdrive and soldered in the new board. Now it works on any computer, mac or PC, is powered off a single USB port, plays DVD's without any extra software, and matches my macbook perfectly. It's also very solidly built, and as an additional plus, the macbook's superdrive sits safely tucked away in a box, while the less expensive 12.5mm drive in the external superdrive gets tossed around in my laptop bag. With a little automator and key remap software (about 10 minutes of work) you can even get the eject key to spit out the disk. It's also bootable, I really consider it the perfect DVD companion to the macbook.
So for about $60 I think I got a much better product than what MCE offers, and the adapter is cheaper and better fit than the newmodeus one.
Still, I might spring for one of the OWC or Maxupgrades adapters if they can hold 12.5mm drives in the uMBP's as that would be a big benefit, especially with 2011 models having a SATA3 connection only in the hard drive bay.
My 2 cents ; )