I will say from my experience, don't always judge a book by its cover. I'm still using my old G-16 Starter Mogul as my main Whittier yard goat and Connelly logging loco, and even with the sawmill at Tier 5 she's had no problems keeping up. She can bring down loaded log trains from Connelly L1 (5 cars) + L2 (7 cars, the max that will fit in the loading areas), then swap them for L3 (I think 9 cars) without struggling. She also has no issues shunting the loading sidings, though it helps that depending on car length you can only shift 6-7 cars out of there at a time. But even when the incoming and outgoing trains are at their full length she can still push them around with minimal struggle. Point is, she's a lot pluckier than you think.

tractive effort and adhesion are important but remember they all have different fuel capacity and turn radius

I run a T22 for the log run up Connelly and back to the mill 2-3x a day (11 cars). It used to also handle the filled cars coming out of the sawmill at night, but at Tier 3 into 4 the T22 started struggling up the hill with them. So now, the T22 just does the log run and the SW1 handles all the car wrangling. That switcher is a beast.

The G16 runs my passenger line, and that's it. I have a C55 doing the Robinson Coal Gap run.

No moving wheels? Add power until it does.

If train aint moving? Add engines until you have the power to move.

I bought the SW1 to replace the G16 mogul and T-17 Sierra RR engine. So I dont have to double head them in the forests of Connelly fetching logs.

I will be looking over the engines carefully because I hear stories of the grades approaching 4.5% and would want to buy two or three F-71's and make the train move in a timely manner.

kinda sucks its so linear. i hope we get some shunters and oddball things

It is my understanding, yes. The cost per "power" is pretty linear. Get what you need for the job because you're not losing that much money for buying a more powerful loco.

For instance:
2x P-18 Pacific has 36k Tractive Effort and costs $14.8k
1x K-35 Logging Mikado has 35.4k Tractive and costs $16k

Just the peace of mind of not having to daisy-chain and control two locomotives is worth the extra $1200.

So despite the fact that the cost per unit goes up, the real benefit is having the power concentrated in one engine instead of several to achieve the same effect.

This is actually really cool. Thank you for doing this math for the rest of us stat nerds!