I can imagine a DE would be a cool weapon to have. I definitely want one for my collection. But practically speaking, I know I would much prefer have a smaller sidearm that's not so large, heavy and cumbersome. Never tried an airsoft or real-steel version, but I know the Umarex pellet version of it is huge and heavy. I personally wouldn't want that extra bulk and weight on me. In real life, I can see how the stopping power of a real .50 Desert Eagle could be of use and make it worth the weight / size tradeoff for performance. In terms of airsoft, I can't see that gun perform any better than any other airsoft pistol that's much more compact in size.
I have a KJW M9 and a WA "Perfect version" Beretta 92FS, and I think those are more compact, lighter, and accurate as hell (well, the KJW is - the WA version is being delivered today). The KJW will be my sidearm for my future games.
But then again, I'm a noob too and never played a game of airsoft to date, so what do I know?