I think you're tallying me in that "couple and half" so I'd like to clarify. I didn't say the ?: operator is always less readable than an if/else block. I only meant that the ?: operator is less readable than an if/else block when you're doing two different things, especially to two different variables. $y = $x ? 1 : 0 is fine. But if you're trying to set one of $y or $z based on $x, well, just saying that is complicated. The code should always reflect the (human) thought process that it is describing - a little extra verbosity in the code to reflect extra spoken verbosity is a good thing. (Please don't take that to extremes. I'm not advocating useless extra code here.)
As far as understanding it - yes, I expect my junior coworkers to understand it. Just not abuse it. Perl, like English, has a natural flow to it. If you try to say something with an unnatural grammar, people may understand it even though it may jar their ears to hear it. Similarly, perl's natural flow can be disrupted and the code still works.
If your code follows the natural flow of the language, the listener (maintainer) who comes along will be able to just read your code. When you do tricky things, you disrupt the maintainer's flow, and they'll need to do a double-take to figure out what really is going on there. If that isn't the problem area, they just wasted time deciphering something that turned out to be irrelevant. And that just annoys us maintainers ;-)