Brad, it was my remark about running empty and only using 3~4 gears, and I agree with you to a point, but there is another side...I will openly admit that my t-19 does get the job done, it also labors the engine in the process. On just about any decent grade if I have anything close to 10k behind her I am taking every gear up to the govenor to get up to speed; not because I am getting any more power, but because the ratios are so widely spaced that if I dont I end up totally out of the power band (2nd to 3rd is a great example with a nearly 1800rpm drop). This also becomes an issue when pulling grades at freeway speeds....If I can sit right at 62~65 she pulls along no problem, but if traffic drops below about 55~57 mph I have no way to hold speed and am stuck grabbing 3rd and dropping to 45 mph (and then winding it totally out if I need to get back up to speed.
My point is that even now my truck has no issues pulling 10~12k on a fairly routine basis, where I have the issue is that with the factory setup what you get is 2 "get it moving" gears (1st and 2nd), and 2 "road speed" gears. Essentially there are only 2 fairly narrow ranges where the motor will be working most effeciently. Adding gears gives you more area to work with.
The same argument could be made for not needing 4 lo....rarely do you actually NEED it, but its alot easier on everything when you dont have to hold your foot to the floor.
Unfortuantly our trucks are not powerhouses that do well outside their powerband, personally I have found my truck is happy flat-landing in the 1700~2k range, and pulling grades in the 2400~2800 range. The tranny setup that is going into mine is geared to have a ~500 rpm between each cog. Granted I will probably never see the need to run sequencially through all the gears, it will be very nice to have a sweet spot gear for just about any road speed up to 70....and total weight is 732lbs (admittidly not totally light, but for the advantages I think well worth it)