Macbook Retina 2.3 8GB vs 2.6 16GB?

[fun_to_travel]

I have a mid 2012 retina macbook pro with 8gb ram. I'm trying to think of any equipment I need for work before the end of the year so I can write it off as an expense. I'd sell my current one.

Problem is when I load up several programs, especially with a large excel spreadsheet things start running a lot slower. I realize most of that is RAM and my fault for getting the 8gb (soldered in). Activity monitor shows about 1.8GB free most of the time, even during heavy load.

Do you think the same laptop with a 2.6 and 16gb ram will be worth the upgrade? Or is it just going to be a very minor upgrade?

Thanks!