I don't think it's just a matter of timing a traditional carry and a slide carry and assuming that whatever's faster is better.
There are many pros and cons of each method, and the whole vault needs to be considered - not just the run. In particular, it's more about the plant and takeoff.
There's a definite speed advantage (and comfort advantage) in running down the runway with one hand, compared to two. This is mainly due to the free arm being able to swing like a sprinter's arm. Monteo, your time trials should verify this.
But a bigger concern is the ease of the plant, and the speed on takeoff
(so time the last
3 strides, not the middle
3 strides or the entire run).
I haven't tried this, but I would think that the technique is less complicated to learn when sliding the pole into the box, than than with a traditional carry and a drop plant. So especially for beginners, there's a good advantage here.
Thus, if the vaulter is more aggressive (i.e. faster) on takeoff
with one technique or the other, that would be the factor that I would look for in trying to decide on the worthiness of the slide carry/plant (or not).
It's interesting that most of the replies in this thread were in 2004, when Tye Harvey was vaulting, and very few since. I don't think this technique (as a training exercise or as a competitive vault technique) should be ignored, just because it may not be as popular as 11 years ago. Or maybe it's still quite popular, but just not discussed on PVP as much?
And with Tye Harvey vaulting 5.70 with a slide carry, no one can say that this technique is only
for beginners. However, my guess is that once you master a traditional/weightless pole carry and a drop plant (which is much harder to learn), the advantages of the slide carry would diminish. If I recall, Tye used the slide carry while he was injured (he couldn't lift or plant the pole with his injured bottom arm very well).