I get the whole diesel truck thing, but for occasional towing of an enthusiast vehicle, the 200-series will surely suffice for motive power.
Even in the hills. Hear me out...
While everyone likes to talk about torque... at speed on the freeway, it's all about HP. I contest that a 381hp (401tq) 200-series can make it to the top of the hill, towing a load flat out, ahead of an F250 Super Duty Crew Cab @ 450hp (925tq), towing same said load.
It's the very definition of hp, to do work, and move loads up hills - "One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second"
But the F250 makes more hp... true, but it also has a curb weight of 8300lbs, vs 5750lbs for the LC. So say a trailer weighs 7000lbs.
LC (5750lbs) + trailer (7000lbs) / 381 hp = 33.46 lbs/hp
F250 (8300lbs) + trailer (7000lbs) / 450 hp = 34 lbs/hp
I don't need to know torque to figure out which setup has the power advantage.
Why, because power (hp) is a product of torque * gearing. hp = tq * rpm
Which gets to my other point. Gas motors are made to rev. Let her rev! It's a Toyota after all and own't hurt a thing. To 5600rpm for max hp. That lets you take advantage of hp and gearing to put the torque at the wheels. Which also means that some of us with big AT tires probably suffer from some gearing loss, and hence perceived performance. Stock sized tires will do better in this respect. The new 8-speed transmission will do better overall, and deal with upsized tires better as well.
I won't dismiss the advantages of diesel though. As it can be more relaxing to access grunt vs rpm to make the power necessary to haul the load. Also, as they are forced induction engines, they suffer from slightly less power loss at elevation. But then again, the 5.7 is a smooth motor. It bothers me not at all to let her rev on grades. I've never not been able to accelerate on a grade, and can definitely stay ahead of rigs as I wish (to burn gas!)