Depends on what you're riding. If you set the fork up right, you'll almost always use all the travel, you'll just likely have better small bump compliance. I don't really care to much about that TBH. I rely on my fork as an ass saver for mid-to-larger hits.
As far as the geo - the data says slacker is always better for descending, and I don't disagree. Where it becomes an issue is length. And that comes down to how your trails are - are they steep and straight, or mellow and twisty. Mine are the latter, so I tend to feel real nice on the shorter, steeper bikes. They are also generally pretty smooth except for medium hits that are sporadic, and bigger hits like jumps and drops, which are more sporadic and optional. Again, for me, compared to my rigid bike, the fork is letting me go faster through the medium stuff and not go around the optional bigger hits.
And then say, comparing this to my (former) modest FS bike, with 130/115 (older smuggler), my speeds were just higher all around. Our level of jumps were easy, drops like butter, chunky sections just pump through them like they were rollers, climbs easier due to better rear traction. I like riding all 3, but I think at some point, the rear end is just holding you back too much to make much of a difference for raking out and adding more travel to the front end. JMO.
