60mm vs. 80mm Spotting scopes?

[CalHunter]

Anybody use both of these at dusk in the field? Will I gain that much more if I upgrade to an 80mm scope? Thanks.

 

[DEERSLAM]

My buddy and I went out one evening right before dusk and set my 65mm Swaro next to his 80mm Swaro and took turns looking threw them until dark. He was pissed he spent the extra $ and now had to carry a bigger scope.