I've used coco mulch as well with no real problems, except in the first week or so I must have kept it too wet (Great point about it holding onto excess moisture Nick).. The potting mix kinda grew a little extra hair as a result lol, but since then it disappeared and everything was fine. It's not my first choice, but it'll get the job done! Lol just be aware of the "excess moisture" retaining qualities and don't let your pooch near it if you have one.. Supposedly poisonous to dogs.. It smells REALLY GOOD btw, made me crave a hershey's bar every time I walked passed the pot! Lol
Best of luck! Also check agway like Adelmanto suggested above.. They carry pine bark mulch.. Just make sure its not "Pine Mulch" That one is made from the whole tree, not just the bark so no bueno as potting mix ;)