THis is not an opinion poll, just a question on experience... I recently picked up a BLI Mikado (last Friday) and immediately put it on the track. After break in, started pulling 20 Micro Trains cars around the layout. After about 4 hours or liesurely running, the loco started starting and stopping intermittently. I pulled it off for the weekend preparing for the old return to sender. This afternoon, I decided to give her another chance before calling for help and it ran flawlessly for 4 1/2 hours. Today I limited the load to 14 cars. The loco was starting and stopping last Friday like it was running on really dirty track of with caked up wheels. Today not the 1st issue. Any ideas?
Paragon 3 is known to have issues, and when Broadway announced Paragon 4, they partially addressed them. From what I understand, the HO motors they were using had a stall current draw of over an amp, which the Paragon 3 board wasn't designed for. I'm not sure if the N scale models suffered from the same fault. This could explain your issue though; your longer train could have been putting too much strain on the motor.
That is my conclusion also. I have plenty of heavy steam power so I suppose I need to limit the Mikado to moderate loads.
I had similar issues with the Pacific.........I haven't tried this, but a friend has several Katos that do the same thing. He was told by Kato that the issue is not with the motor load, it's with the amp for the sound. He was told to turn the volume down, and it seemed to work on the Katos.