Lets clear the air:
61.5 and 148 are mirror images of each other. 61.5 eastern us and 148 western us
61.5 still has the voom channels, international, & sky angle
129 carries HD including HD locals if available, it will also carry some SD locals if available
500 + and 1000 + will carry some HD locals for certain markets and international
The type of dish that is required depends on the type of programing subscribed to and were the customer resides.
A second dish for the 129 may increase signal slightly, but if the signal comes down at 30 degrees for a 1000 it will still come down at 30 degrees with the single dish, tree or no tree.
Check out lyngsat.com for programing per bird. Dishes web site will tell you what orbital each channel comes down on, you have to go through each channel individually though. Back in the day some markets required a second dish for additional local channels now all locals can be picked up with one dish.