I owned a 1.0 XBox with a Matrix chip and ran that for about 8-9 months. Apart from the odd re-aligning problem it was great until I dropped the XBox and completely wrecked it
A few months ago I bought another XBox 1.1 and installed an X-Killer chip (I went for this because I wanted a solder solution this time so I didn't run into alignment probs, it was also very cheap ($30AUD - paid $130AUD for Matrix chip)).
I installed the chip using the wire method, so if I needed to take it off in the future for whatever reason it could be easily done. I have never soldered before but got it first time and have never had a problem since. I'd post a pic but I don't think you can on this forum.
I run EvoX dashboard 3752 and X-Ecuter BIOS. It does everything the Matrix chip did except give me alignment errors.
dzv, are you sure the chip only has 256k? I'm sure it is 1meg, 4 x 256. Check out this link under "Multi-BIOS". Check it out.
There's a bunch of info at www.x-killer.com
I don't really care about the flash protection either