A first review of the already ten year old R1 / R1C1 macro flash kit is online. It will be interesting to see, if this kit will be updated to the new radio trigger system of the SB-5000 in the near future, or if is just being sold in parallel.
Sales of the kit seem to have been moderate. Currently sold SB-R200 flash heads have a serial number of 217****, which would indicate a production volume of a bit more than 170.000 individual flash heads. If we assume that at least 2/3rds of those were sold as part of a R1 or R1C1 flash kit, this would make a bit more than 55.000 kits with two SB-R200’s included in ten years.