Cheesy,
All I can say is, go for it if you can afford it. 400 yards is enough to work out a .50 and yourself as a shooter with it if all you want to do is have fun. If you aren't going to be shooting formal competition, get one of the 'carbine' versions of the uppers that fit on an AR15 lower. With a shorter barrel it's a little more wieldy, and not so much hassle to move around and store.
I just took delivery of a 22" barreled upper from Walter Keller at Safety Harbor Firearms, and decided to go ahead and get one of his new single shot lowers to build it on rather than using a conventional AR lower. Overall length of the complete upper including muzzle brake is 35 3/4" and weight with no sights etc. is about 14 pounds. It'll take down (after it's built up) the same way the upper and lower receivers separate on an AR, by punching two pins, and the longest part will still be less than a yard long.
And the thing is a piece of art- excellent design, incredible metalwork as far as the machine work, fabrication, welding etc. is concerned. I am really looking forward to getting this one to the range, and my wife can hardly wait as well.
Essentially there's nothing else exactly like shooting a .50, and if you want one and can manage it financially that's enough reason to get it IMHO. It was enough for me anyway- even though it meant selling off all my .30-06s (one Garand and two bolt guns) to manage getting it. And you can reload for it too... 8^).
lpl/nc