Depends on what kind of data you have. Since I use it for Pictures, Music and Video, I use snapshot. I make sure things are stable and that the only changes to the pool are additional material and occasional deletions. I make sure that my scrapers aren't constantly changing my metadata. Media Center Master can be bad about this. Real-time still has some limitations to it such as a single PPU at least at the moment and requiring all drives to be spun up. Over on the forum, I see people getting into a lot of trouble trying to restore their data. In ascertaining why, turns out they're doing stuff like including live buffer from a tuner card into the pool. Snapshot isn't made to support data that is constantly changed.
Here's a link to some discussions: http://forum.flexraid.com/index.php/topic,1251.msg9745.html#msg9745
and here: http://forum.flexraid.com/index.php/topic,1342.msg11319.html#msg11319
, the second post. There are many others.
Part of the problem is the wiki DOES NOT have a clear, concise, step-by-step setup guide discussing setting up Flexraid. Most of the info is there, but spread over a hundred different articles. I can't find any reference to turning off the Windows recycle bin for pool drives in the wiki, I only know about it from forum discussions. Even Assassin's guides, which are quite good, makes no mention of the Flexraid recycle bin.
All-in-all, Flexraid is perfect for HTPC use, but it's not real-time raid and the documentation could be a lot better.