Assuming the mine on test today matches the one that came live - this is not true. The Endless Coal Mine is affected by the geologist skill that enables faster mining of coal ("Quality Coal Mineshafts"), enabling production of 30 seconds. If you place a 2x2 storehouse in the position next to the center coal mine in S7, you can achieve a 42 second cycle for the center coal mine and a 50 second cycle for the upper right coal mine if you get a second one (like the copper, it maxes at 3).
In addition, the Endless Coal Mine produces +1 coal per cycle, so under optimal conditions, the Endless Coal Mine (level 6, quality coal mineshafts, best storage placement) is producing 7 coal every 42 seconds, and a second mine could be producing 7 coal every 50 seconds unbuffed.
Last, the coal mine should be affected by mining zone buffs, while the recycler should not be.
If anyone has the mine and confirm the above came over to live servers, I would appreciate it, but the math tells me the best mine placement can achieve 1 coal per 6 seconds, while the best placement for a level 6 recycler is 1 coal every 34 seconds, so the first one can be close to 6x more effective (second one 5x) and uses no building space.
Additional note: it looks like there's a 2x2 "gingerbread storage" building coming on test. which will fit very nicely in the space next to the center coal mine in S7...