i don't have direct experience but lots of forum members use them. i bought a package this year and never used them mainly because all my other germination methods were successful.
i do use coir containers but can't say i notice any big benefits from the coir alone, most likely because i then bury the coir into a 1 gallon container of soil.
the brand i bought are Planters' Pride, the Jiffy site says their Jiffy-C7 is the only peat free product on the market but i guess they didn't do a google.