The magic chips are harmless to your console but they aren't all too great. The only real difference between 3.5 and 3.6 is that 3.6 was supposed to add support for dvd9 games. There are still a lot of problems with the Magic 3.x mods. You can read charlie's review of it
here. It is the second to last post. If you want a superior chip, get a Messiah 2. It costs a little more but is problem free unlike the Magic. Send charlie_ps2 or dust2dust an email if your interested in purchasing a Messiah 2.