I have used both. Same results. The only reason I give the edge to the RR is that I hated cutting the mesh away from the Jiffys when it was time to move the babies to a new home.
I don't remember taking the mesh off last time I transplanted thought it said to leave it on and roots grow through could of been another brand
I like coco too, but the pellets are so convenient. What do you mean when you say "liners"? How do you keep track of what is what?
I'm also a fan of rapid rooters for no muss or fuss involved, so grats on the score :p Not everyone can get ahold of a wicked mix like Mike can. :p