Before buying an Android device....

If are a geek or technical guy before buying and Android device you have solve this question.

Is the bootloader unlocked?

If the bootloader is not unlocked you may have this problems:

• Once the manufacturer drop the support of the device you will not be able to install custom ROMs under you own risk
• The product may have a software brick and you will not be able to recover it. 

So, always asks for a unlocked bootloader.