I used to have a mod-chip on my old Playstation 1. I had one fitted as I was going to America, and wanted to buy loads of NTSC games, lol. (I live in
the UK). I had no problems with my mod-chip... It was in there for about 2 years, but then my Playstation went down - Not because of the mod-chip, but
because the fuse which controls the controller ports blew (a common problem), so I couldn't play any games. I just went out and bought a PS2. Not
getting that chipped yet, but may do as I am going to America again next year.
My brother in law is thinking of getting his PS2 chipped, (for legal purposes). He wants to get the new swap method style, forgot it's name. But you
simply replace the PS2s case with a new case, and you use a boot disc to load up the backup games. Search on any PS2 mod-chip website and I'm sure
you will find it.
So if you don't want to solder anything, I would go for that method. And as it's fits all PS2s it's a good idea.
I have never installed a mod-chip myself, but was thinking about it, as it's much cheaper than paying someone else to do it for you. I don't think
their that hard to fit, depending on how many wires you have to fit and how many chips yo solder.
Most mod-chip websites actually have a tutorial section where they show you how to fit them, plus most mod-chips come with a manual. I wouldn't
personally go with an internal mod-chip for your PS2. I would go for the swap method, as it can't from what I can see harm your machine.