Peeush,
I'm definitely in the 'against' camp - though it depends on what sort of flight profile you're talking about. Medium level (500ft MSD and above), with good obstruction data, it is probably OK for the HP to be flying RNF (ie no NVDs) and the NHP using them for 'nav assist' during transit or obstacle avoidance during a RNF approach to a runway or marked HLS. At low level it's a no-no; in the UK it's not permitted for front crews to wear different Gen tubes. Why? So that both crew see the same picture and there's no confusion. The same confusion can happen with one crew on a FLIR and another on NVGs - careful CRM is required.