I disabled autocorrect but left predictive text on. This has been much better and it exposes either how bad of a typist I am, or how bad the system is guessing at which key I meant to type.

I use the predictive bar to fill in or correct when it gets it right, or I go back and tap on a word to see if it has the correct replacement.

The main deficiency that caused me to finally disable is what you mentioned - Changing words that were correct when I typed them.

I erase my dictionary from time to time. I made bad puns so I know that does not help the system.

Also based on which keyboard is up, I will get an extra n or @ when I meant to hit space. Disabling autocorrect has really helped me to see these input issues.