That kinda stinks about the lost production until the failed unit is replaced. Hopefully they won't take a month like Enphase has for the last couple of units I've had to replace.
I did have a look at the SolarEdge website
and I do not find anything there that says you won't lose the entire string if an optimizer fails. Of course they don't say that you WILL, either. Instead, they tell you have incredibly reliable the optimizers are.
How long have you had your array? I saw a post in the Tesla PowerWall thread indicating you had it in early May, which was over two months ago. If you haven't had it much longer than that, then I would say this is likely just an infantile failure and nothing to worry about. Unless you have additional failures, it shouldn't be a big deal (except for the lost production).