Nexus 6p for a Huawei Mate 9 in an even trade?

So I've got a guy heavily interested in my 5 day old Nexus 6p 64g. He's got a 4 month old Huawei Mate 9 in box with contents and wants to trade evenly. What would you guys do? I love my 6p but I've always wanted a Mate 9 also and I love EMUI. Let me know your honest thoughts and advice on what you think of the trade. He also wants to buy it but I like having one larger screen device in my typical two rotation of phones I have. One being smaller for my daily driver and one being larger for my movies and media. If he were to buy it then I know what I'd buy and it wouldn't be a larger screen phone as I have my eye on a Sony Xperia X right now which that is a perfect 5 inch phone. So that would leave me with two smaller screen devices. What do you guys think I should do? Thanks in advance.