I prefer mechanical to electric or hydraulic because the ancient coal-burning brain cells suss levers better than electrons, and (as said) you
might be able to fix it.
Trying to find an air bubble in 30 feet of hydraulic system with 5 components and 17 joints does not yield to profanity, or even self-mutilation (proof on request).
Detecting a bad ground that "always worked before", but has now decided to visit another galaxy is another example of "how to make bloody holes in your palm with your fingernails".
The non-converter PG I've seen has a simple valve that bypasses part of the valve body line pressure that engages low gear. Valve closed: must be pushed, but no loss/no slip. Valve cracked will allow the engine to idle in gear (brake on!!) to check for leaks, linkage, etc. Valve open 25% allows the car to be "walked" slowly by blipping the throttle softly. The valve could be a motorcycle type clutch lever, pedal, or large twist knob - driver's preference and interior space factors.
Since this was developed to allow trailering and pit movement only, I have no faith that it could be used to actually launch the car, but it might reduce driveline stress when used with a push-start.
As to terminal speed for different boxes: it's only a general rule that as speeds go up, and RPM at peak power goes up, that a tight (small % drop) shift into high gear has more value. Cars that are traction limited or have very broad power ranges (diesel, turbo) won't follow this path. No original auto trans that I know of has a useful 2-3 or 3-4 shift (although the 4L80 is pretty good at 75%), but it's not necessarily going to hurt every time. IMHO super-close ratios (less than 10% loss into high gear) are not useful unless the torque curve has a big spike in it, and dead on either side.
Some common ratios:
http://victorylibrary.com/mopar/aod.htm
