Dave,
When I started shooting 260'/sec with an overdraw back in 89 that was extreme speed for the time. Going to 300'/sec won't gain me enough to bother with. Not to mention you get to the point ofbeing unstable with big broadheads. I have no desire to shoot expandables. And I am blowing big holes out the back side of elk at 40yds now. I will stay with what is working. All the new fancy design that is out there and carbon arrows can't kill them any more dead than what I am doing now. Plus my big old logs are putting less stress on my bow and my broadhead are still flying true out at 80yds. Do I really need more? And the truth about arrow flight is the right match of arrow/broadhead for the bow and perfect tuning. And the shooter has to be able to shoot his/her set up. I have been around the game for some time now and see way too many people trying to shoot the new fastest bow out there that is poorly tuned and they have crap form. They can't tune it because it is too high tech for them and are very unhappy when something goes wrong with the bow in the field. My set up is very simple and dependable. This attitude may make me anal, so be it. Butwhen I walk into field I am ready to kill an animal with one shot and there is no question ifmy set up or myself can do it.I can live with that.

Back to the issue of X vs +, as the arrow starts forward on the rest the initial thrust from the bow string is where the broadhead starts planing. An air plane starts gaining lift as soon as it starts gaining speed. Once the arrow leaves the string the vanes/feathers take over and guide the arrow to its target. So it is of great importance how you get the arrow off the string. This is where all your tuning, arrow shaft stiffness vs poundage come into play. The X reduces planing pure and simple.
Gselkhunter