Should I upgrade a Macbook pro 13" 2014 to a 15" 2015?

Specs on my 2014

• 2.8 GHz Dual-core i5
• 16gb ram
• Iris 1536 mb graphics
• 256gb ssd
• 7 battery cycles (just had battery replaced)

Specs on 2015 (Craigslist) – $1450

• 2.5 GHz Quad-core i7
• 16gb ram
• Iris pro & R9 M370x graphics
• 512gb ssd
• 290 battery cycles
• AppleCare until May 2019
• Purchased in 2014 (?) – think he means 2015, but either way it's not a recent purchase or refurb. Looks to be good cosmetic condition.

I'm going to be traveling for several months here soon. My home-setup is dual external monitors. I'm not keen on being stuck with "only" the 13" display for that long, so I'm looking at upgrades – specifically, the aforementioned 15".

I'm honestly pretty happy with my 13" right now, but with all the issues the newer MBPs seem to have, I'm hesitant to choose one of them over a 2015. I have a lot of peripherals already, and don't fancy having to buy just as many dongles. Not particularly optimistic about this September, either.

I use my MBP for everything except the occasional game, which I have a separate rig for. I'm hoping the M370x can be a workable substitute for that while traveling. I don't play anything serious, just WoW with old friends to keep in touch. I do development work, so the quad-core i7 might be a nice upgrade. I also only have 10gb of storage remaining on my 2014, so extra space will be welcome.

I'm mostly concerned about the cycle count. The capacity isn't yet low enough for it to be replaced under Applecare. Given that, and the fact that it's "3 years outdated", is this a fair price? A good idea?