As long as it's a Harley, you can rest assured it won't be 100% reliable (or even close). So while the new style tensioner system is an improvement, there is nothing I've seen that says it is foolproof. As Brad mentioned, some folks have had them fail very early. Others have had them misassembled from the factory, and I'm not convinced they really solved the chain quality issues they had with the old style parts. The new chain is a roller chain that in theory shouldn't chew up the shoes like the old style chain often did, but Harley and it's suppliers have many ways to screw up the best theories.
IMHO, I'd be inclined to add a couple items to the 25k checklist just based on the failures being reported over the past few years. I'd add a check on the tensioners and a very thorough check (or replacement) of the lifter rollers and bearings. Checking the tensioners is relatively easy (I don't buy the 15 minute claim though, since most exhaust systems interfere with removing the cam chest cover), but removing the lifters for inspection or replacement is a little more involved.
JMHO - Jerry