There is a 7 1/2' 5wt Fenwick glass rod around here that gets used a LOT in the tube.
If you are having trouble hitting the water behind you with a 9' rod, a 10' rod will only add a foot of distance to THAT spot! Like JC says, "keepeth thy backcast uppeth" will serve you better than a long rod.
If you build your rods, you can somewhat "balance" it by adding a few corks to the foregrip, thus holding it a bit further up.
We DO like our 10'er. It is a 5wt. We succumbed to the temptation by reasoning the advantage in mending and lifting more line over the poop in the ponds. It does that. It does keep our backcast about
1 1/2' higher than the 7 1/2' rod does.
....lee s.