No. synchronized_value doesn't takes in account shared mutexes.
Please create a ticket if you find the feature useful.
I'm not sure yet because I'm not in a position to check if there would be a performance impact in my use cases by replacing mutexes (as shown in the example)
by shared mutexes and associated locks. I suspect that there will be tens of concurrent info() calls while m_info is modified, but I don't know
if it's worth using a shared_mutex for such number of accesses.
I will have to measure before getting back to this point.
A bit of bikesheding: I like synched<T> as a shortcut name (but I don't think that's valid english).