I tolerate zero blackout. If you have to hold your bins in some awkward position to avoid blackouts, then they aren't the right bin for you. one thing to clarify -- it's really more about YOU and the shape of your face and the way you hold them than anything, a particular model doesn't "have blackout", it's just a question of how its specific combination of eyecups and eye relief combine with your facial structure and holding style.
you should definitely find a pair that works for YOU in this respect.
Eitan speaks with much wisdom, however, it should be noted that certain binoculars such as the Nikon SE cause image blackouts for so many people that it goes beyond user dependent features. It's that "anal aberration of the exit pupil" (saw one guy write this once and had to laugh, he meant "annular" though most of the time I've seen it written as "spherical aberration of the exit pupil"). As someone pointed out earlier, that's what "SE" stands for.
With the SEs, I experience some image blackout with the 8x32 and 10x42 models. Not with the 12x50 even during the day (used it mostly for stargazing). Not sure why since they all have the same EP. One of those Nikon mysteries.
If the SEs had a reasonable sized twist up eyecups (most WF porros have twist up eyecups that are two wide for my eye orbits), I think I could mitigate the blackout problem better since I could set the ER at the proper distance for my individual eyes. My right eye is set slightly further back then my left eye, hardly noticeable in real life, but when eye placement is critical, every mm counts.
With the SE's fold down rubber eyecups, the choice is either all the way up or all the way down. One guy, think it was Claudio from Cloudy Nights, managed to use rubber bands to get the eyecups in a halfway up position. I tried it, but couldn't get them to stay that way. Must have stronger rubber bands in Italy.
I think if you can modify the eyecups some way with washers or rubber bands, etc., then its worth trying to adjust to the bins if the optics are superb.
But unless you are a diehard porromaniac like me, there are so many good choices out there with roofs that you're bound to find ones that fit you better.
It's your cross to bear. You are either going to need to modify the eyecups or use the MOLCET or limit yourself to bins that don't cause blackouts for you.
My buggers are sensitivity to "rolling ball" and issues with "nose relief".
So to finally answer your question, yes, I am willing to put up with image blackouts to a certain degree, but if an optic requires superincumbent (Word-of-the-Day) contortions to avoid blackouts, then it gets black(out)listed.
Brock