Don't get me wrong, Many fine blades have been, and are still being produced in coal forges. I even keep a bucket of coal in the shop, and occasionally set a few small pieces on the front of my propane forge just to smell the coal burn. This brings us to forges. I have tried most every make and model available commercially, and many others that where formulated within my, as well as other Blacksmith's and Bladesmith's shops'. Through experience, I have formed some very pointed opinions of what a good Bladesmith's forge should, and should not be.
Ceramic blanket has it's draw backs too.
After years of playing with different types and designs, I have settled on a circular design that uses Castable Refractory, with a forced air burner. I recently built a new forge of this type when the refractory in my old forge got a little thin. In my humble opinion, a knife is more than a certain type of steel, or a specific Rockwell hardness. This includes not only what type of steel to use, but how that steel will perform at a given hardness, plus, how all the other aspects of the knife blend to produce the finished product. Things such as, blade geometry, distal taper, weight, and balance.