I've used coir, and find it a good material for citrus. The pH of coir is, depending of it source, 5.5 to 6.8 which is correct for citrus. Depending on the source of peat, the pH of peat is 3.6 to 4.5. An extra good point in favor of coir (at least for me) is that when dry coir is a lot easer to rewet than peat moss. Growing in mediums such a 5-1-1 or 5-2-1 where the drain through (water pass through) is rapid, coir retains more of the water than peat, but still allows for the higher oxygen level for the roots to respire. Chemically, coir which comes from the coconut contains potassium, manganese, copper, zinc and iron. I like coir.