AFAIK, all 3ware raid cards will work out of the box on SME 5.6. There is a "generic" driver that seems to work fine.
Having said that, however, if you want to use the web administration software from 3ware (3dm), you may be in trouble. The first problem is that you will need to manually install it (their script file doesn't understand the SME's runlevel 7). Secondly, their 3dm app either won't work at all, or won't work properly unless it is paired with the same level of driver and firmware. Since there is no info on what driver version is included with SME 5.6, you are into a guessing game, and while I've attempted to do this, I have not been successful. (Using 3ware's drivers requires you to compile from source, and that too has been disappointing in the past)
But I've found that the controller works so well, and so reliably, that I can safely do without the 3dm.