The article you linked only discusses the Xonar and does not mention anything about the Xtreme.
Creative cards have usually had an edge in their surround sound implementation (positional audio) for games during the EAX days. Where they fail is they're generally more problematic and bloatware. Creative cards have the latency issues since their pci sb, the sbs would hog and make poor use of the pci bus and cause crackles/pops. Being a defacto monopoly they studiously ignored complaints and have never fixed the issue. Their pci-E cards may not have the issue because the signalling protocols are different.