Yeah, that card has been a total PITA for users. It works for some and not for others. I don't think anyone has commented on it with 9.x. I'd say if it doesn't automagically work its probably not compatible.
Plus, highpoint controllers, if you try to run them in legacy mode, require you to setup the partition table in a very very odd way. See
http://forums.freenas.org/threads/highpoint-controller-info.8217/
Additionally,you may not have SMART monitoring or SMART testing, which really hinders your ability to identify failing disks.
Quite honestly, that's one of the last controllers I'd have tried because there's so much confusion on when it works and when it doesn't. The IBM M1015 can be bought for about $100 on ebay(cheaper than the 2720SGL), reflash to IT mode and then it is the ultimate SATA/SAS controller for FreeNAS. So many people use the M1015 that if there was a bug that affected the M1015 you can be sure someone is on top of it quickly.
If you are hellbent on making that card work, the only advice you're likely to find here is "good luck". There's so much conflicting information on the controller's compatibility and functional status and without actually having one to test and experiment with, you are on your own to figure it out. Generally though, if it doesn't work out of the box it isn't likely to work.