Towing this with 3/4 ton

A higher ratio differential will put the transmission gears closer together but also restrict the range of your transmission. You have to ask yourself if the restricted range outweighs the benefit of closer gear changes.

Sort of. If by restrict the range of the transmission you mean possibly lowering the top speed of the truck when not pulling. Say 90 mph instead of 100. It will restrict the transmission range if you truck is capable of max rpms at top gear. Most of us don't use that capability but if you do go blazing cross country at 85 or 90 it may make a difference. I'm not putting you down if you do, more power to you.

For pulling you are always better off with lower diff gears resulting in closer ratio final gears. Everything else being equal.

BTW this is the main problem I have with my Tahoe. I have a 2000 rpm shift so when it does shift I go from being at the top of the power band to just below. I essentially have one gear for pulling hills. 2nd. 1st will get me up the hill at 30 but not fast enough to get into second. If I had lower gears I could make the shift and be on my way.