Have updated to DSM 6.1 and again have same issues with ttyUSB drivers not recognized.
I had to install ones from Jahlal aka jumbotroll, then change rights to 777, then restart zwave service to get zwave to work (+php link trick :p).
I then restarted my syno and drivers was not correctly loaded again with rights issue.
I saw that PulseStation modules are launched through : /usr/local/etc/rc.d/S99Modules.sh
This script is unloading system USB modules and loading the ones from Pulsestation from /var/packages/PulseStation/target/active, then changing rights.
I think Pulsestation USBserials are not up to date with my system, then it fail to load modules and to set rights.
How to update usb modules from pulsestation?