Locks that work

These seem to be different locks with the x - plus 54 lasting much longer than the x-plus from grinder cutting. Below are the quote from the 2 different reviews

X - Plus (2009 review)
"Moving onto the power tools, our angle grinder did cut through the Xplus in 59.8 seconds, but under attack from the regular bike thief the Xplus is more than enough"

X - Plus 54 (2010 review)
Our portable angle grinder took a whole 4min 43sec to get through both sides of the shackle – that’s just 17 seconds away from a complete pass, and for a portable lock it’s a superb result.

Not sure if this would make any difference to the overall score of the x - plus 54 but it was confusing me regarding the wrong links

I get the impression that in the earlier test they used a mains-powered angle grinder (~2000W). Those have much better cutting performance and can cut pretty much anything in no time. The battery powered portable ones (~800W) take a lot longer to cut a lock.
I had older and newer X54 in hands and they seemed identical. The only difference i know of is that the locking mechanism has gotten more sophisticated over time. Current X-plus cylinders have multiple "fake/trap" disks which make them harder to pick.