Sabrina,
Peat has advantages, but has its share of negatives too. One thing that may be affecting your Always Afternoon is the fact that peat can be very difficult to re-wet when it dries, and once that happens, the water you apply will tend to flow downward through a few "channels" without wetting the entire root zone. As you've discovered, clay can move around in a soil mix, almost self-distributing, so if you add a half-inch of clay-based soil as a top-dressing around Always Afternoon, the water will soak in more evenly, and repeated waterings will intersperse the tiny clay particles within the peat, which might help a lot.
I've had many different brands of "normal" potting soils get to the point where they dry and resist re-wetting. I top-dressed the containers with an inch of native garden soil, and the percolation and rewetting problems pretty much stopped.
A lot of coir is generated every year by the coconut industry, and they have to do something with it, so thanks to an impressive marketing campaign, it seems to be a part of almost every soil mix available. Overall, coconut coir has been a mediocre performer for me. It seems to hold just as much water as peat, but lacks peat's antimicrobial properties. I lost a lot of South African winter-growing bulbs due to rot the first year I used it. (That mix was 1 part coir potting soil, 1 part perlite, 1 part pumice)
Last year I tried a coir/perlite mixture with a few mature daylilies in 3 gallon and 5 gallon containers. I like that it's easily resettable and (due to the perlite) has good, open structure, but it lacks any nutrients whatsoever. Despite using a complete "hydroponic" fertilizer with micronutrients, the mature daylilies showed lackluster, weak growth, with thin leaves. It's better now, the magic bullet turned out to be a Calcium-Magnesium supplement recommended by the maker of the potting mix, so I think I'll let those daylilies go one more season before repotting into a more conventional mix. Last fall, I planted some daylily seeds in 3.5" pots with the same mix. I had figured out the Cal-Mag deficiency problem by then, so they did fine from the start. The seedlings continue to grow well, and the water-holding capacity of the coir is really appreciated now that the seedlings are getting larger and thirstier.
One good thing about quality peat is that it tends to break down fairly slowly, the true test of coir will be how it holds up for several years in a container. The best potting soils used to be made with peat, sand, maybe some perlite, a touch of loam, and ground bark, and it was well-composted. Now, time is money, and there is a lot of wood recycling going on in landfills, so fir bark (a magnificent, but costly product) seems to have been replaced by the vastly inferior ground pine. A lot of the wood chips are so raw that they are being dyed black for eye appeal, and after watering they slowly return to their original tan color. When pine starts to decompose in a container, it's highly susceptible to fungal growth, and the resulting mycelium will render the potting mix essentially waterproof. This seems to be particularly bad when mushroom compost is part of the soil blend.
