I was hoping they were at least close. People report problems with coil chillers in half-batches (coil only partially immersed) and I was hoping that eliminating the coil chiller entirely (and condensation, etc.) might be an answer.
I can cold crash from ale temps to 38F (with Spike Cf-5 and Icemaster 2 glycol chiller) with the Spike cooling coil overnight--amazingly quick. I've never measured it, but I am guessing it's about a 5 degree drop per hour. Maybe more. I doubt the energy transfer would be nearly as quick with a fridge.
My needs are more focused on cold crashing than maintaining ferm temps. I now see this argues even more for the chilling coil because the coil is faster and I wouldn't need to put up with drippy chiller hoses for more than a day at a time. The short duration of a crash also makes using an ice water reservoir more palatable (vs a glycol chiller) because it should only need to be filled with ice once. Who knows, I might decide on a glycol chiller eventually, but there's a chance the ice is convenient enough. (to be clear, I'm talking about pumping ice water from the reservoir through the chiller coil)