[inlinenl]

I assume you're going dig.out to your hedd dig.in

if you're going dig.out from nuendo ( in 32bits ) , there will be auto-truncation to 24bits on your audio-card , which will feed the dig-in on the hedd.

so you can choose to save to 24bits with dither before mastering or just doing/trusting autotruncate ..... it's up to you ....

32bits storage is more interesting if you'll do some ITB processing before or after the mastering.
but before sending it out off you audio-card it's not really a benefit.
IMHO