What is the best way to update Prestashop 1.5 theme to Prestashop 1.6

[SmartDataSoft]

Hello,

 

Just need some idea from other Prestashop expert. Nothing else

 

There are some theme for our client which is build with 1.5.5+ standard. They want to update that theme to 1.6.

 

So any one have experience what is the easy way to update.

 

Here is some idea.

 

1. Some developer suggest that build 1.5 theme to 1.6 from scrach. They told that 1.6 change huge

2. Some told that no need to build from scrach. Just move the js from tpl to global.js and all js work.

 

So any one have any idea other that this , or you are well come to share your idea.