But differences may arise across your group of 9 enlargers due to a variety of variables including alignment, focus, lens, negative, negative flatness, contrast/filtration, print processing, safelights, print viewing conditions etc.
You also need to define exactly what it is you mean by quality in the first place.
If someone perhaps less experienced reads the thread, how can he/she come to meaningful conclusions without knowing how the tests were done and how the results were evaluated? What if someone else fails to see what you see? Who is correct?
Michael, as you correctly point out the variations across even 2 enlargers is enormous and this snap I mention is not just about a contrast difference as mentioned in other posts. I have printed the same negative on a condenser and diffuser and after adjusting for the reduced contrast on the diffuser I produced two prints from which I could discern no difference. I suppose what I’m trying to say is that given a negative ideally exposed and developed for a condenser against a negative ideally exposed and developed for a diffuser, the one produced on a condenser below a certain physical size exhibits a sort of snap quality not shown on the diffuser version. I know this is very unscientific, but it is something I have observed over many years.