From what I've read, people in the northeast have a problem with "continously picking up 129." So this may not help you, but I think I would first give it one more try; by re-adjusting your dish so that you get a stronger signal on 129 and a weeker one on 110. Possibly even trying with the strongest on 129 and see if you still have 110. If you lose 110, or its not strong enough, back up a little - keeping 129 the strongest.
Before moving anything, make marks of the current settings as a reference point to go back to, and you'll be able to possibly pick a happy median.
Although "dnsguy is correct," it's not the height that matters. With CB and other various radio communications, height may make a difference in signal quality, but with sat tv, you either have a line or sight between your dish and the bird, or you don't. The 500 is lighter and easier to work with than the 1000 and especially the Superdish 121, so if you need to go higher, then use the lighter 500.
If you decide you need two dishes, then think about this...
If the 500 is a DishPro Twin for 119/110 mount it correctly and use it for 119 and 110. Then use the Dish 1000 to pick up 129 adjusting it for maximum signal, even if when you are finished, it has no signal for 119 and 110.
As dnsguy said, a bigger dish is better, and the 1000 is bigger than the 500, so you should be able to make do with what you have.