My Matrix has also been working well for over a month without losing alignment. Just like soldering, if you do it right, it will work good.
globalhec: Sorry, but I don't buy into a single word you are saying. First how can you have said this a hundred times with only 36 posts.

Second, where is the solder going to move to touch something vital.

...there's no way something like that would ever happen.
Finally, I've had a lot of experience with these chips, and it's my opinion that these chip lose alignment due to the attachment screw. If you are lucky enough to get a 'Matrix-friendly' Xbox and are careful not to strip or overtighten the original screw, then you probably won't have these problems. Also, I have not heard from a single person who used the longer screw that I've been suggesting and have alignment issues after that.
Nailed, I totally agree with you; soldering elitists will never get the point. As elitists, I'm sure none of them have ever actually touched a Matrix. As such, they have no experience to speak from; just what they've heard, so their comments are pretty meaningless.
I might not be l33t, but at least I can remove my mod in a matter of minutes and upgradge to another mod without much trouble at all...try that with your solder mod.