Excellent step-by-step guide.

Yes, Apple should not be torturing its customers (completely on purpose, this is 100% intentional) but at least it makes this nasty process easier.

Upgraded the RAM (and swapped the original 5400rpm HDD to an SSD while at it - the hard drive swap is easy once the screen is open) and the difference is very significant - probably gives the iMac an extra 2 years of life. The SSD upgrade is probably the much bigger performance boost vs. the old SSD but the RAM upgrade once the screen is open is difficult to resist.

Well done iFixit as always!