@Duncan62 I think you are missing the point. I am confident that nobody here is intending to insult you or claim that your tank is not successful.
The question of this thread is about nitirite toxicity specifically. You seem to defend that it is toxic and fish should not be subjected to it, but contradict your own claim with the use of damsels for cycling instead of a fishless cycle. Instead of providing any studies or information, you seem to keep providing only anecdotal evidence and emotional appeals.
Research seems to show that nitrite is not very toxic in marine environments and is mostly considered an issue because of its high toxicity in freshwater tanks.
It seems that most issues come from other factors common with beginners for fish deaths in improperly cycled or new tanks as opposed to being attributed to nitrite.
@Lasse is providing a different perspective with some research backup. This is more inline with the thinking that we still do not know all details or aspects of reef-keeping, so continual studies should be done. Different opinions work in a beneficial discussion if scientific methods and rational arguments are made rather than using logical fallacies and only touting our own opinion. It's best if we present valid arguments with research and documentation to back them up and address and counter (if necessary) the arguments posed against ours.
I still wish we could answer the question as to how harmful or stressful nitrite is to fish, but it seems to me from what I read that this is not one of the most important questions that beginners trying to understand cycling need to ask. Of course, longer cycle time before fish introduction seems to be always better to ensure complete nitrogen cycle.
This also brings to question, though, whether measurements of ammonia converting to nitrite and then to nitrate are enough for complete cycle indication. What about cases where the overall ammonia amount is not as high as the introduced fish/invertebrate/coral bioload and there is not enough bacteria to work fast enough to overcome the ammonia introduction rate? Maybe there is enough bacteria to make the conversion over a length of time, but it really seems like there needs to be a measure more relative to the intended bioload. Is this currently maintained by reaching certain levels of ammonia that are converted within a certain time-frame?