Thinking about buying a new laptop... Options?

Hello !
 
Looking for opinions on a couple of topics regarding the ever-ending question "what should I do best to upgrade ..."
 
Currently have a 6-7 years old Dell Studio 1745 Core I7 1st gen laptop, 4 gigs RAM / firewire based rig. Cannot afford to both change the laptop AND the audio interface at the same time... 
 
I have 2 options: 2nd hand or NEW laptops.
 
Option A : 2nd hand LENOVO T430 (Core I5 2nd gen as I understand... at least as powerful as my actual I7 first gen, but only 1 internal drive). It has USB 2 (good news for my TASCAM legacy backup interface) and USB 3 ports and an express card slot (for firewire). Would upgrade RAM to 16gig... I should be obtaining a slightly better performance than my actual lappy, while opening up to newer USB3 interfaces. Around 900 CAD$
 
Option B: New LENOVO Thinkpad P50 laptop. (would put 16gig RAM... looks like it can have a 2nd internal drive)... USB 3 only, but again with an express card slot AND Thunderbolt 3... Close to 2000 CAD$ of course! (But... will thunderbolt ever gain momentum on PCs / audio manufacturers?) 
 
For both these scenarios, I'm keeping my fingers crossed about DPC latency spikes and other hidden jokers (Been plagued by that on my actual lappy).
 
I would guess the used T430 could keep me running for a good 5-8 years without spending too much or feel too limited... I'm Tempted to go down that path...
 
Otherwise, the brand new P50 lappy sure looks great... stretching my budget a lot, though.
 
What would you choose?