Deals on 2013+ MBPR15, and another "which to buy" thread :p

[Halfakorean]

I had a early 2013 MBPR15, absolutely loved that machine. Until I graduated and couldn't find a job, which led me to selling it. Finally found a job in my field, and now I'm looking into purchasing another one.

For my own usage, I will be using it for light coding in multiple IDE's, and casual gaming. No video editing, some light photoshop. I found that the 8GB (in my 2013) felt a little sluggish at times running multiple applications, and planetside 2 ran like complete ass in places like the Bio Lab.

Current configurations I'm looking at are:

early, late 2013 MBPR15 with 16GB, not even sure if there was a 2014 release, and the 2015 with current AMD dGPU.

My question now is, are any of the models after the early 2013 worth it? My thoughts are:

• I wouldn't benefit from increased processor speeds from any model (all games I played before were bottlenecked to GPU)
• Is there really that big of a battery difference?
• I lucked out with no screen ghosting on my old MBPR, but do any of the newer models suffer from the dreaded ghost/yellow screen?
• All benchmark and fps in game tests are hardly distinguishable between the models (<10% between early 2013 and 2015). Anyone notice real world differences with gaming?
• No need from a higher r/w SSD.
• I always prefer to future proof any large purchase, but struggling to find the price difference justified. Early 2013 ~ $1100 (used), 2015 ~ $2300 (amazon)

*edit: When I say deals, I mean: *looking* for deals. Sorry about that.