I am honoured that you should seek my view on this. There is a NEO4 - it has 44 wires and boots all PAL originals and CD backups no swap. PS2 Import originals (useful US originals for example) are NOT supported; DVD-R and EA CD-R backups require a single swap. It's a crap chip for what it does in my biased opinion. It is very difficult to install. Having said that, purchasers of the NEO4 have bought it knowing these limitations and profess themselves satisfied, generally.
There are two games in town for your PS2. The Origachip for Pal (
www.origachip.com) - 15 wires, boots everything incl. import originals. Costs about £25 plus shipping from Italy. Takes a couple of hours to install but you need to be a good solderer.
The second game in town is the Messiah. These are very expensive because demand is high and availability is scarce. This is a complete no-swap solution and boots everything - EVERYTHING NO SWAP. I won't go into the cost here but if you e-mail me via my profile, we might continue this discussion.
Hope that has helped.