I have used coconut coir many times mainly for rooting cuttings of roses. The coir doesn't cause the cutting to develop mold like using regular potting soil and some other types of planting medium.
It really works well.
I have never used it when potting bareroots or budded maidens or bands. I only use professional grade potting soil I get at my local nursery. It is kind of expensive at
$21 for a big bag of it, but it quickly makes up for the cost when it helps new plants live and thrive better and even can make the difference in life or death of the plant altogether.
John

HMMM,,,just be careful with coconut products. I know cocomulch will kill dogs if ingested so I wonder about the coir since that is also a coconut product (great for outdoor mats). Sorry to interupt but thought I'd put that out there....

Cocomulch that kills dogs are made of the husk of cocoa. coir mulch is made of coconut husks and are not eaten by dogs

I am pleased to report, all of the coir I spread still looks as beautiful as when first exposed. No fungus gnats, no crusting or mold, this is the perfect mulch for my garden. It protect and covers, looks wonderful and all my plants seem to love it, some ground covers even root into the fibers. Please save our peat and try coir instead.

Ca I use mulch cypress chips on top of the coir?

See:

http://rosebreeders.org/forum/viewtopic.php?f=2&t=55285&p=63093&hilit=coir#p63093

Henry, I would love to see what rose breeder website says about coir, but that link doesn’t work for me.

Stephanie, I tried looking at it with my wife's computer, and it loaded ok (she is not a member of the hybridizers group). Did you click at the end of the second line?

I was able to open the link. The article makes a good point about coir products, and I recommend rinsing for salinity. I ordered some from amazon and it was so salty the rinse water smelled like the ocean! :-)