I have a larger brother 14" Commercial Ektar. The quality certainly impresses me! These were commonly used in advertising and commercial catalog production (hence the name "Commercial") up until the early 70's---maybe even longer, and were well corrected for color.
I have used my 190mm/7.5" Wide field ektar on my 8x10" camera and it's great. Stopped down beyond f.16 it covers with room for minor movements, and for contact printing it's high quality to the edges. I bought it on ebay a few years ago and since then it's my absolute favourite.