RE: Just Chrono'd my XT
 

A few pounds on the draw weight makes very little difference on the output velocity so shoot what is comfortable. On my Mathews Ultra II one pound makes 1 fps difference. At least from 60-65 pounds. I also use a peep and tube for the reliability and never having to check my peep before drawing. Not a big difference for deer from a stand, but huge when spot and stalking IMO. I lost no velocity with the new tube peep, but I did also go to a upgraded string, so maybe they cancelled each other out.

RE: Just Chrono'd my XT
 

My stats:
[ul][*]draw 27"[*]G5 peep (5 grains)[*]D-loop[*]GoldTip 7595 Pro Hunters @ 26.5[*]125 Gr Tips[*]66#[*]blazer vanes (2")[*]Vapor Trail Sting & Cable[*]Vapor Trail Limb Driver rest[*]STS[*]Switchback XT[/ul]
The total arrow finished arrow weight is 413 gr and it shoots @ 259 through my chrono. I've toyed with GT55/75's with a 100gr tip which came in at 271 with an arrow weight of 363 and CX300's with a 100 gr tip @ 266 with an arrow weight of 386.

I went for the heavier shaft which shoots great and is extremely quiet. I use the bow strictly for hunting and I want one that's quiet as a church mouse. With the heavier shaft, it's very very quiet. I plan on using this setup for deer, bear and hogs.