I first heard about Mosaic around the time that their Monk and Clifford Brown sets came out - but then promptly forgot about them for 15 or so years until just before the end of their vinyl era. At that time, importing such sets into the UK was a bit of a step into the unknown and few retailers stocked the Mosaic product. Since then I've been making up for lost time, trying to get the sets I missed (and especially in the LP format). Just wish I could have got those Commodores when they originally came out !
I can't say there has been a single Mosaic that I have regretted buying. I've made forays into Harlem stride piano, 50s vocal music (Froshmen etc) and New Orleans jazz, not my usual territory at all, but in each case the boxes have been truly enjoyable and ear-opening.