To use "dp" (Device Pixels), or not to use "dp"; That, is the question.

So I keep reading around (and I believe I saw in the documentation) that using "dp" (device pixels) is the best way to setup your UI. From experience with 6 different Android phones now, this has got to be impossible. If it were that case, I'd have to create multiple different layouts for difference size devices. Using just the integer (20 instead of 20dp) gives me pretty much the same result across all 6 devices. Why does everyone keep saying use "dp" instead of without it? Are you not running into the same issue I am? Using "20dp" on a EVO 4G looks way off compared to a Samsung Galaxy S III and then other tablets. Now, I'm wondering if this will happen on iPhone's now with the retina vs non-retina phones vs iPhone 5 screen-size increase.

dp is the way to go when you need to support multiple screens. Don't take your initial tests for granted. There will be instances where things just won't scale on Android (especialy on small displays). So Density Pixels (not Device Pixels) is the only way to ensure that an object will have the same proportion regardless of the screen.