I have not had any issues with the 890 motor. The design of the bases are surprisingly deficient of good design and seem only to excel at inspiring regret and lack of confidence in the tool. Traits normally associated with lower tier tool names.
The fixed base will neither easily release the motor nor lock it in place with any degree of accuracy. After locking the base the depth adjustment is usually off. Getting the correct depth setting is a trial and error affair. And with the fine saw dust that collects in the channels, preventing reasonably easy removal of the motor, I am skeptical that the motor is able to be locked-in perpendicular to the table top.
As for the plunge base, it has slipped on me, which is a bit of a problem when using a flush trim bit. The base slipped down a quarter inch, lowering the guide bearing below the template. I only discovered this after the piece I was routing was damaged. I had never even considered the possibility of the plunge base slipping. Now I have serious reservations about using the plunge base for template work.
The PC 690 and 7500 are established, proven designs. Milwaukee and Dewalt are also highly regarded. Based on my experience, the PC890 should be avoided.
Measure twice, cut three times, start over. Repeat as necessary.