Possible installation scam? M2 Pro .. Ver 6 Ps2

[sumpm1]

I tried to install a messiah pro 2 about 2 years ago on my ver 6 ps2. I FAILED!!!! When I booted the machine all I got was a black screen. I recently sent it in to a reputable installer and they said that the machine worked fine after they reversed my installation. I payed for an install, and then they told me that after installing they found that my M2 Pro was a firmware ver 1.08 and is not compatable with ver 6 ps2.

I was under the impression that m2's were compatable with all ps2 versions. Is this possible?

I requested that he trade me for a compatable chip because I have no use for it. The first option that he gave me was to buy a new chip: a Duo2 for $20, and a DMS3 for $25. He offered some other more expensive chips including an M2 Pro, but I would rather go for these cheaper cards.

I have been out of the loop for a while, I don't know which of these cards would be the best, I assume the DMS3 because of bios flashing.

Tell me which of these cards would be the best.