What should I take nexus 5 or be with my moto g?

I'm really confused what should I do. Here's the problem, my moto g is good but I it heats up a lot like going to more than 45°C, and fed up of this but I still love it becoz it is my first android phone. Now android l is coming out next month and I know that lenovo has bought Motorola, and Motorola has almost stock android, I bought this phone becoz it was cheap and in my budget and I will get the update soon. But I also loved nexus 5 but it was out of my budget now 6months are over for my moto g and android l is going to roll out next month and nexus 5 is a strong and powerful phone in gaming also and will get the update first. So I Thought If I Would Buy Nexus 5 Second Hand, I would get a powerful and which will get update soon also. BUT I'm ALSO THINKING WILL IT BE GOOD TO BUY A SECOND HAND NEXUS 5. Like I don't know if I take a second hand I may get a defected piece so I'm also afraid and how to tell my parents. I saw in quikr site about second hand nexus 5 which were at 10k to 15k which is in my budget. But is it good to buy and sell my moto g? Or buy and keep my moto g and give it to my brother? Or I don't know what should I do? Please guys help me I love nexus 5 mobile a lot please give a solution thank you guys.