Xcode doesn't have a public plugin API. Every single one of these packages, including Alcatraz itself, is relying on undocumented and unsupported functionality. I would very strongly caution against installing any of it.
As a user of several of the packages available on Alcatraz, and Alcatraz itself, I strongly disagree with eridius.
If you do have issues with a particular package it is pretty simple to remove any/all of them. The only time I have had issues is when I've tried to run betas of Xvim on unreleased versions of Xcode.
Seriously, if you're interested at all in the packages made available through Alcatraz give it a shot.
No, Apple gave up and implemented a compatibility UUID system to try and reduce crashes (since any Xcode crash is going to be reported to Apple and Xcode engineers have to figure out what happened, which means Xcode engineers get bug reports triggered by unsupported third-party plugins).
The existence of the compatibility UUID does not mean that Apple has blessed plugins. They're just trying to reduce their support load, and reduce their users' crashes at the same time.
If you do have issues with a particular package it is pretty simple to remove any/all of them. The only time I have had issues is when I've tried to run betas of Xvim on unreleased versions of Xcode.
Seriously, if you're interested at all in the packages made available through Alcatraz give it a shot.