Yeah I'm fine with the 18-speed. It's almost fun. I'm not so good at it though. I think the problem is that I'm used to driving an older truck with a stiff, manual throttle pedal, so I'm used to the engine taking 3 seconds to fall from high RPM to low RPM. With the S60 in the semi, it's about half a second and it's at 700 RPM. Simply being faster to shift is helping. By the time I've pulled it out of gear, it's just about right to put in the next gear straight away.
I'm also not so good at driving for better fuel economy. I guess a super b with 500 HP isn't going to be that efficient anyway. Just seems like I'm always working it hard. Takes me a long time to get up to highway speed too.
I agree with Northern Farmer. The 18-speed gives you options. I mostly drive it like a 13-speed, but in and around the field, I use the lower splits a lot.
Allison has their new 10-speed full automatic (not auto shifting) that's rated for 600 HP, 1700 ft-lbs torque. That in theory could pull a super b, but it's not certified by Allison for loads that high. I've read reviews that are pretty glowing. Constant acceleration makes things very smooth and way better on fuel. A locking torque converter removes a lot of the inefficiencies there. And with the jake brake on you get constant engine braking all the way down. No abrupt removing of torque between gears while speeding up or slowing down. Maybe some day they'll release one that can handle a super b. They are twice the cost of an eaton manual transmission, and not available except in brand new navistar trucks thus far. With fuel efficiency regs coming down the pipe, it's possible that manuals (full manuals anyway). I'm sure there will be gnashing of teeth, but in another generation, no one will care. Kind of like how we all love our CVTs on tractors now.