Heroku doesn't auto manage your dyno and workers based on usage. You set dynos at 10, you're running 10 throughout the month. Likewise with workers.
Heroscale ramps your dynos and workers up/down based on necessity.
Also, can your service scale workers all the way down to zero and then spark up the first worker upon the next job submission? Or can it only scale workers as low as one?
I'm familiar with the "pilot induced oscillations" from a first hand basis, scared the crap out of me. The desired scaling quality is quick ramp ups and then gradual, minute based ramp downs. This is to handle a sudden influx of traffic to the site. We don't just peg your dynos anytime something comes in. And the free accounts are set at 3 max, so don't worry about it blowing up your bill.
Dynos are ramped up fast as a response to incoming traffic and average wait times per request. I'm still refining this algorithm so feedback during beta would be awesome.
The algorithms for workers are slightly different than dynos since they feed of different info. The answer to your question is yes, it will scale down to zero if you have nothing in the queue. You can override this by setting server min and max thresholds for workers.
Drop us a line at contact AT heroscale DOT com and happy to talk more.