DMS4 chips will work on the new PSTwo. Here's the news from DMS:
PS2 Slimline - Breaking news!
DMS Team have had the slimline USA PS2 slimline in our hands for several days. Testing shows that our FPGA code already supports booting burned medias on the new system. Therefore the DMS4 Lite and Pro will boot burned progarms on the new PS2 by default. The Eject solder point has been removed, however we have found an alternative point which can be used to provide the functionality required by our FPGA code We're now working on installation diagrams and they will be online by the time our MODS hit stores early next week. Once again DMS lead the field with innovation and confirm first support for the new system. Enjoy