I think I've found the answer to whether or not we should use Pvlinks when configuring our volume groups in HP-UX - the answer being no. It's only recommended to use alternate links when booting from a storage array, which we don't do on any of our HPUX hosts.
From the powerpath admin guide:
EMC recommends using LVM alternate links (PVLinks) when you
boot from a storage system. If the primary path fails, an automatic
switch to the alternate path occurs. If PowerPath is not installed,
using alternate links increases availability in the event of hardware
PowerPath uses alternate links as part of its boot/root failover
strategy, but not for load balancing, path prioritization, or other
PowerPath-related reasons. Thus, EMC recommends that you use
LVM alternate links when booting from a storage system. Otherwise,
EMC recommends disabling PVLinks when using PowerPath.