I have to admit this is a pretty low priority for us for several reasons, especially because it’s difficult to know with any level of certainty what the copy number is for a group of bacteria. What is the copy number for a member of an uncultured phylum? For the Lachnospiraceae? etc. Also, when we are comparing communities, it is done on a relative basis and so if a bacterium goes up or down, so will it’s rrn copies. If you want absolute numbers, you are best off using qPCR on a single copy gene. Thing like normalize by copy number are at best a hack.