We couldn't get Hyundai to honor the 10 year/100,000 mile warranty when the catalytic converter melted down on the 2001 XG300 earlier this year. (my mother-in-law makes very short trips very slowly...the XG only has about 45,000 miles)
I don't think using MaxLife ATF is going to change their minds and the warranty is surely expired by now.
The 10/100 Hyundai warranty only applies to engine, engine accessories, and transmission. Catalytic converters are covered by the Federal Emission Defect & Performance Warranty, which is good for 8 years or 80K miles - whichever comes first. But don't let me rain on the parade. Carry on.