I'm running the panasonic series on the PM25. I'm running some clearpath servos on a completely different piece of automation, but have found they are excellent for the price.

From what I've seen steppers suffer from missed steps, a lot of flakiness from poor quality drivers, lower and inconsistent speed/torque and a lot of vibration. There are some that use feedback (hybrid) to fault on missed steps, but the smoothness factor just isn't the same. I was surprised to see how much of a difference it made cutting an arc. The challenge of course is when people go down the stepper path it is a lot of jumping around upgrading this part and that part until the final project costs the same or more than if they had used servos from the start. I worked in the automotive industry for many years so this is a very familiar story. If you start with the cheapest option, you often spend a lot more in money and frustration. Buy it cheap and buy it twice.