Yes, it matters. You must have firmware 2.0B for model W512EB... I have not tried the newer firmware C or D. I know B works. Do me a favor and try D after downloading it from this link. If it doesnt work I will help you by searching for the 2.0B firmware update. If the firmware D fails I will regret discarding the firware 2.0A - B update. Hopefully all the firmware updates work with everything and have not regressed. As long as you get a drive that has 2.0A firmware your fine since that can be updated to 2.0B firmware. Only about 5000 of the 1.0A-D firmware drives were manufactured and they are not clonecd compatable and dont have the burn proofing software and cannot be updated to the 2.0 firwares. Do not, I repeat do not, purchase this drive used on ebay since you will more than likely get the 1.0A firmware version. It is best to purchase it new in kit form in a sealed box from a reputable vender. I believe if you get a kit it has to be firmware 2.0A or higher. Additionally there is a firmware there for the W512SB model which is for the scsi version of the drive so ignore it. It is not for your drive.
http://www.teac.co.jp/dspd/download/download.html
To Repeat: This teac drive fully supports clonecd including write simulation, has burn proof, has a 4mb buffer, overburns and is just plain old reliable. I have tried to make it fail and it just wont! It is relatively inexpensive going for about 160 shipped. The plextor comparable model only has a 2mb buffer, cannot overburn and cannot perform the write simulation test with clone cd although that feature is hardly used these days.
Balls, said the Queen if I had them I would be king!