My X-Chip was the first xbox chip I'd ever installed. And it was a pain in the ass to install (solderless). It wasn't so much that it was difficult as it was lengthy. I spent roughly my whole day messing with my xbox. Taking the xbox apart and putting it back together was annoying, putting these tiny rivits in the holes.. Getting that wire in D0 (finding the right hole was very easy though). After that I had issues when I was putting the machine back together the chip was getting bumped or something and losing contact and would cease to work. After many many trys, I got it back together and it's working (for now atleast).
Overall I'm quite pleased with my X-Chip, while it was a pain to get working I didn't have to solder anything. That was my main concern with getting an Xbox mod. While I understand a soldered mod would be more stable as it wouldn't lose contact, I can't afford a soldering mistake and my soldering skills are slim to none anyway. I'm sure everyone knows if you can solder go for it, but if you can't, the X-Chip will work for you. It may be a pain to get it working at first but you'll be pleased when you have it figured out.