[A/S] Transmission Pros and Cons

[James Newton <newton_j@xxxxxxxxxxxxx>]

I'd be interested in a discussion and anecdotes of listees on this topic.  
 
I notice that most professional truck drivers have manual transmissions (with many gears) 
to keep their big diesels running at the optimum RPM.  I guess that the direct mechanical 
connection between the engine and the drive wheels on the road is more efficient (no 
slippage), but what about starting on a grade, negotiating through heavy traffic, etc.  
I've pulled my A/S through San Francisco's hilly streets once (LOL).  Also, what are pros 
and cons regarding the engine/transmission combination (diesel-manual, diesel-automatic, 
gas-manual, gas-automatic).  We generally have much smaller engines (either diesel or 
gas) than the big truck drivers.
 
Comments?
Jim, now in California