The 7595's are a 300 spine shaft as well.........they have a 5 layer construction that I think differs from the regular Ultralights and I believe they are a tougher shaft. (I am trying to go from memory here) I think the 7595's are only about .5gr heavier per inch as well. The fact that they are a bit heavier per inch of the same spine tells me they are the more durable shaft with a thicker wall.
Over the length of say a 29.5" shaft (guess for a 31" draw) you are only adding about 12 grs of arrow weight.
What components were you thinking for a 425gr finished UL300? That seems a little high?
I would tend to go for the little thicker walled shaft regardless of the extra weight. (You can always make up weight on component choices)
There's a reason why they offer 2 similar shafts in weight and spine of the same diameter and I wouldn't be quick to choose the one designated for target use over the one ear marked for hunting.
Now if you REALLY want to flatten the trajectory? Look at the 22 series shafts. They are really light and actually VERY tough. They are stiff as well........something like a .250 spine? A finished arrow weight could easily be under 400grs with a 100gr head.
I shot them all 3D season last year and they took a BEATING....literally. I had to replace countless bushings but no destroyed shafts except for the robinhoods of course.
Whatever you decide on, scrap the plain GT nocks and get some uni bushings in those shafts or it realy doesn't matter what you choose.......they'll crack.
I'd suggest the pin nock system which I like very much but I don't know how much stress those little nocks can take with 400gr+weights and the energy you are putting out.
Plain ol' Unis and G nocks will do you just fine.
I'll be hunting with a 70# /30" Allegiance for much of the 2006 season and I'm choosing the 7595 Pro-Hunters, I might have you a bit in the energy Dept too.
Regardless, any finished arrow of 425grs or less out of that bow is going to look like a lazer beam.
I would rank the GT shafts for your set-up
1. 7595's (PRo's or XT's)
2. 7595's camo hunters
Then for #3 I'd think about the "Play" choices like the 22's which wouldn't be a bad choice if you really want a flat shooting bow but realistically is lighter than you need to go.
Frankly I wouldn't have the plain UL300's in my top 5 for a hunting shaft choice from GT.