Yes and no. The water doesn't fundamentally change anything, all it does is add moisture so that when it Cooks the meat and in particular the white meat doesn't get so dry. It just makes it more moist.
What matters more is the salt, which breaks down the dense proteins that normally would contract during cooking and force the moisture out like squeezing a sponge. By not having those there it retains more moisture also.
This is why dry brines are basically just coating and salt and do much of the same thing.
No doubt that Brian's make them more moist. The trade-off is that you actually lose some of the flavor because it will see back out into the brine while soaking, and the flavor is literally watered down.
Personally though I HATE dry meat, especially white meat, so the trade-off is worth it to me.
The real challenge with properly cooking a whole turkey is the difference in temperature needed to get the dark and light meat to get it "falling apart" cooked (denatured protein). The dark meat needs to be like 170 to 180, while the light only needs to be like 150. Getting that white meat so much hotter for so long really tries it out.
That's why the brining really helps no- it prevents dryness in the breast.
I'm personally of the opinion that the best way to do it is a dry rub and then cocksplaying (slicing open and laying flat) so the dark needed just as much exposure as the breast. But it's not practical if you have a particularly large bird.
