DND_Reborn
The High Aldwin
Not really in either case IME because just about 80-90% of everything in the game has the same speed, and the creatures that don't have the same speed are nearly always faster than the PCs....1. The "out" isn't so much the moving and Dashing - it's the hiding. Cold comfort for someone in heavy armor unless they roll particularly well, but there are ways to mitigate that (Inspiration or working together, for example). I've used these rules a lot (or modified versions of them) and it's all about the hiding since that's the means to escape.
4. The existing chase rules work for this, if a bit clunky in my opinion.

1. PC disengages and moves 30 feet. Monster moves 30 feet and attacks, repeat until PC dead.
OR
2. PC flees (dashing), provokes OA. Monster dashes to re-engage, repeat until PC dead.
You can't take the Hide action under direct observation in most cases, and if you are Disengaging or Dashing, you have no action to Hide anyway...
(bold)
Now, your modified versions might work better and are good enough for you, but using RAW unless I am missing something, they pretty much suck.