Well, I would have to say 4 lb of fresh would be roughly equal to 1.5 of dry, depending on what you were taking. Given that when I'm eating freeze dried, I'm usually rehydrating with 2 cups of water for dinner, and 1.5 cups for breakfast (that doesn't count coffee) that should mean I'm adding in roughly something less than a kilo (about 2 pounds) of water.

So, by the reverse of that math, assuming I'm adding a kilo of water to rehydrate food everyday, all other things being equal my rehydrating my food might save me 2.2 pounds a day. Yes, absolutely on a short trip if eating fresher food is important to you, that's an easy tradeoff to make.

Depending on how "real" your food needs to be, on an overnighter you could also ditch the stove. just take stuff pre-cooked, or buy two big taco bell burritos for dinner take bars for breakfast and you may be ahead of the game. Personally I could handle the cold dinner just fine, but the coffee monkey on my back screaming at my brain in the morning I probably couldn't take...

One other problem with "real food" however is that I may need to take more crap with me to make it. making my "kitchen" setup heaver and also adding weight. Personally, I find with a little inventiveness I get enough variety and taste into my dehydrated menu that I'm happy with it, and "forcing" myself to do meals fbc style has the side effect of keeping my cooking setup utterly minimal. When I have "real" food I take a heavier stove, bigger pots - a pan, scraper, etc. all of it adds up.

These days my usual "real food" take is if I'm
gonna head in in the evening on a short hike in to where I've got a nice spot and can build a fire. then it's simple. everything else is FBC, and a foil wrapped good steak, potato, and a litre box of red wine can weigh me down horribly for my first little bit, and I'll enjoy that immensely the first evening.

It really comes down to what you like to eat, and why you're out there. I know from experience that I like eating good freeze dried meals just fine for a week. I know (also from experience) that after about two or three days on nothing but ramen I worry I might start thinking like the Donner party. I also know other people who simply don't like anything they've tried FBC style and would rather pack more "real" food. I personally don't find *good* freeze dried food (good store bought meals or good homemade stuff) blah.