I love mine. I shoot mostly middle-of-the-road stuff, neither super light nor super heavy, and I have never had a problem with any ammo I've used in my DE. The two-stage trigger is awesome and the gun is way more accurate than I am.
Halfcocked got one hell of a deal. I bought a regular black-oxide Mk VII with fixed sights for about $725 several years ago, and I *thought* I had gotten a great deal. But a stainless for $700? DANG!
It is big, but kick-in-the-pants fun. It may not be the most practical choice, but there are few cooler ones! I have never regretted getting it, and I don't think you would either.
I wouldn't worry about the difference between alum and all steel. And I think that anything under $700 for a used but great-condition Mk VII would be a decent deal. The newer Mk XIX's, besides being more expensive, all use the .50 frame (which is bigger and more unwieldy imo), so unless you have big hands, you owe it to yourself to at least feel the difference between the 2 series. My $.02