RE: grunting and rattling???
I use a grunt in addition to rattling but rattling is by far the main thing.
The grunt comes in handy if I want to stop a deer (when it's walking into cover or I just want to get a better look...or just for fun really). Sure, they stop and look if you just whistle at them but if they're hot on the trail of a doe the grunt is better for getting (and keeping) their attention. The grunt I have is a doe bleat when I suck air in so it works well in those situations.
BTW, the one I've got is a Knight & Hale EZ-GRUNT-ER "PLUS" DOE BLEAT. It wasn't a very good choice for here in SK cause it freezes up too easily but I get by with it with infrequent use.