129 issues....
The reason for the drop outs every 15-20 Min's is because Sat 129 is oscillating and they can't stop it. We (my boss and I) got this info at Team Summit.
The resent changes/movement in 129's transponders have been largely due to communications my boss has been having with E*, he is in comm. with the top guys at dish working on the problem, For a while he has been forwarding all his email he gets from customers having trouble with 129 and they have been using him to test the changes they make.
A little over a week ago, E* made an official change for all HD installs in WA. All HD installs get a D500 and a 24" dish (for 129) with a higher quality LNB mainly used in Alaska. They are also upgrading previous installs. There are supply problems on the upgraded lnb (oddly called a LN "low noise" lnb) so they are saying the standard lnb is OK for now. You can tell if you have a LN-lnb by looking at the sides, they are tapered in a bit, sorry don't have pix handy.
We have found in testing the the LN-lnb gains you about 5 points of signal and the upgrade from a D500 to a 24" dish gains 10+ points. Also upgrading from a D1000 to 2 D500's gained about 5 points.
The upgrade doesn't cure the problem but in good weather conditions you shouldn't loose picture during the 20 min signal drops. As the weather gets worse in the Fall I think you will start to see the dropouts again.
Of course the best solution is if you can get 61.5

Mark Jackson (President of EchoStar Technologies Corporation) told me that it would probably be 1.5-2 years before 129 is replaced, that was about 6 months ago, and I am sure the time-line has changed since then.
Sorry if this has all been covered already, don't have time to read all posts.
Brad