So 2011 had to come to the rescue!
Not really, but I was just testing out the pulling power of several of my recent rebuilds, and I ran out of room to add more cars on my tiny little 027 dining room table loop. So I had to make the load heavier, hence the black 1666 on the metal 3650 flatcar. With the full consist of PW (and a couple MPC) cars, Pennsy 2011 (which is a PW frankenloco from one of my other threads, upgraded to PS1 with a Senco tender donated by a forum member) was struggling to get traction on the start, but a slow roll-up did the trick and it did really well pulling this long heavy train around very tight curves at low speed. This is a heavy train with quite a bit of rolling resistance, but 2011 is geared down and uses a different motor than the 726 / 736 that she stole a chassis from. Once she got started she ran smooth at low speed. The variation of speed you see in the video is just the voltage drop on the opposite side of the power drop.
Separately, the black 1666 did just fine pulling the consist (without the added weight of herself on the flatcar) as did the 1666 in the foreground, which I just finished restoring and painting in a Southern-esque livery with Lionel Lines markings. The black one came to me a pile of rust and wasp nests (for real) but cleaned up great!
All three engines, the 4637 tank car and the crane car were junk when I bought them. None of the engines were functional, but using things I've learned from this forum since February, I've been able to restore them all to 100% operation and gave them all a whole new life.
Really appreciate everything y'all contribute here. 
