1) Is there any discernible difference between the EVGA GA and G5 series? Both gold, both same warranty, both full modular, and both have incredibly similar rail ratings.

2) Within the same brand, is there really anything that changes between the 7 and 10 year power supplies? (ie TXM vs RMX, Focus vs Focus gold). The only thing I've noticed is that the 10 years tend to be full modular and the 7 years tend to be semi. Is this just for the sake of more faith that that they can just replace a faulty cable vs the whole unit in that extra couple years?

You kinda answered your own question with #2.

The 10 year units generally have better caps so they just cost a little more.
I use BQ units and TXM units for prebuilds and they work fine for me.

Once you start doing major overclocking and start adding multiple high end gpus you wont be using gold units anyways (Platinum or Titanium)

This website will help with questions like you have...

In the real world there are only like 5-6 companies that make power supplies. Companies like EVGA (for example) buy the power supplies from the manufacturers and brand them as EVGA.
As you look at this list you'll soon notice something. Companies like Seasonic, FSP, Superflower, make awesome power supplies. Companies like HEC, don't.


Main list: http://www.realhardtechx.com/index_archivos/PSUReviewDatabase.html

Who really made my PSU list: http://www.realhardtechx.com/index_archivos/Page2293.htm




Lastly, the best power supply reviews come from Jonny Guru's site: https://www.jonnyguru.com/blog/category/reviews/power-supplies/