What is worth paying a bit extra for is Lenovo's on-site warranty servicing, where their techs will come in to your office within a time interval. It's generally accepted that post-IBM Thinkpads are less "I can take an 18 oz claw hammer to it" than the T40 era tanks[1] but I'm hard enough on my hardware where I managed to bend the corner within 3 months of owning my first-gen MBA 13" by hucking into a TSA container in a morning grog to catch a red eye. (I also have the uncanny ability to kill headphones and fray power cords with ease.)
Hackaday's linkbaity[2] article is somewhat helpful (though a bit late since you seem to have made your purchase already).
As someone already mentioned, with Bash-as-a-first-class-citizen in Windows 10, as well as the general stability of the OS (I've got > 3 months of uptime on my well-abused Inspiron i7 that's coming up on 4 years old and it's as responsive/reliable as Windows 7 was), I have no particular desire to return to running OS X as my daily driver.
[1] www.retropcmania.com/2009/11/ibm-thinkpad-t60-review-thinkpad-t60-vs.html The rigor with which some of the TP aficionados have analyzed their hardware amazes me. [2] hackaday.com/2016/10/28/apple-sucks-now-heres-a-thinkpad-buyers-guide/