Reviews tend to be overly positive (don't want to anger the vendor, your relationship) was done with a Preview copy, or on a well maintained system, not yours, while most feedback is from disgruntled people, meaning the person on Amazon etc that had trouble with the install and perhaps other problems. Then use it just on the clone, or put the backup off line while you try it out.
You can (should) make a backup (bootable clone) of your system if you want to test new software. I would assume you wont' get a straight answer here, or a straight answer directly from the horse's mouth, but you might want to at least check the Symantec Community.
