Just finished my first layout using the new hierarchical interface. I actually liked the idea of a prefix around each block, as it made the PCB clearer which parts belonged to what system (e.g. part of the PSU, main micro, etc).
Unfortunately this allows you to have duplicate part numbers it seems, save the prefix. e.g. I can have a "PSU:C1", and a "MCU:C1". It would be great if these could be renumbered such that the prefix is basically just extra information, but the part numbers are still unique. Obviously it's easy to have someone miss the prefix when assembling a batch of boards! I'm aware of the 'offset' mode you can use as well, but it's not quite the same, as I'd still like to keep the prefix.
I happy compromise would be a ULP which does this, and the user just runs to renumber everything. There is already renumber-sch.ulp but it seems to do a sheet at a time as well. Some sort of global system would be ideal. I don't know how the hierarchical blocks are implemented so if that's possible or not.