Yes,you can disable VLAN1 on 802.1q trunk.
The benefit is security - VLAN1 is the deafut one, also used as native VLAN and management VLAN by default.
But it disables only user data and STP.
CDP, DTP, VTP and other Cisco control protocols are still running in VLAN1.
You also need to configure other VLAN as native one.
You can get in troubles with STP - VLAN1 STP is used for interconnection with other vendors devices (Common Spanning Tree).
There are sometimes bugs noticed related to VLAN1 disabling - I remember VTP not working on Cat3550 when VLAN1 disabled in the past.
Regards,
Milan
