I'm sorry to hear about the problem with the airline but to me it seems like deja vu. I will let others suggest replacement equipment. I just want to tell you all what happened to us a few years ago in a somewhat similar situation. My daughter, who at the time was 16, went to study abroad for a year. She flew on Air France out of NYC in August with a group of about 50 students and a program director. She was one of the last of her group to board the plane. The plane was packed and at the door to the plane, an AF person told her he would have to check her carry-on. It had her laptop in it, as well as a camera, chargers, batteries, etc. She said she saw carry-ons that other passengers had brought on the plane that were larger than hers. She protested that her laptop was in it and that she didn't want to check her only carry-on, but the guy basically bullied her into thinking that if she didn't, she wouldn't leave, and she was young and inexperienced enough that she believed him. So she handed the thing over. And, of course, it was 'lost'. Anyway, as I remember, the replacement cost for everything in there was about $4,000. She, and I, did everything we were supposed to do... she filed a lost luggage claim with the airline before leaving the Paris airport. She even stuck around for another 2 flights from NY on AF to come in before leaving the airport. I contacted the lost and found offices in both NY and Paris several times over the next 3 weeks, contacted the airline by phone and in writing within a week of the loss, sent copies of receipts for the lost equipment. In response, I got a letter from AF saying that the airline had reviewed the case and determined that they were not at fault for this lost equipment, since passengers are supposed to put computers and camera equipment in their carry-on luggage and not in their check-in luggage (!!!???), and therefore they didn't owe us a dime. I protested, in writing, and again got a letter saying that they had again reviewed the case and had come to the same conclusion, basically a FU, we're not paying you a nickel. I took the airline, on behalf of my minor child, to small claims in NYC. Had to go down there four times. The first time, no one from AF showed up, so I was awarded a judgement of $4,000. Then I got a notice telling me that I had to show up again because AF said that they hadn't shown up the first time because they never received any notice from Small Claims. As it turns out, the address that airline has on record (for their corporate offices) with NY State, and which is also the address listed for their corporate office in NY in the phone book, is not, in fact, where they have an office at all. I am convinced they keep a phony address on record and in the phone book for exactly this purpose, to thwart people who are trying to go after them. The second time down there (January), the AF attorney was there, and that judge (a different one from the first) threw out the award and said that the court wanted to hear from the other side, meaning AF, even though the first notice had gone to the address on record. But not just then...it meant coming back a third time. The third time (April), the judge (different judge) said that I should have shown up with my daughter (she was still in school in Europe) but he allowed me to came back yet another time when she was back home. Btw, the prior judge had not bothered to tell me that I needed my daughter with me. The fourth, and last, time (June), my daughter was with me, since she was back from her school year abroad. (Yes, people, we are talking about nine months of this BS.) My case was the last to be heard that night (Small Claims is at night). It was nearly midnight. For at least an hour before that, court officers had been coming over to me to try to convince me to agree to come back another time since it was getting so late. I said no, I was ready to wait as long as it took. Finally, we got in front of the judge (different judge). To make that long story short, the judge said that he felt my case had merit, but that his hands were tied because in the fine print of the airline's contract with passengers - the stuff you never read, and don't have a choice of agreeing to or not, it just is what it is - it says that no matter what, $1,500 is the maximum amount the airline can be held liable for lost or damaged luggage and its contents. So, after several months, much back and forth, a lot of time, effort and expense, not to mention a lot of anger on my part, I got $1,500, plus interest, a fraction of what it cost me to replace the computer, software, camera, batteries, etc. The moral of the story...the airlines suck. They make the rules, the break their own rules, and then they deny financial responsibility, and they get away with it. Never, ever, let them force you to check in your most valuable equipment. And if any airline agent does force you to check in carry-on, get that agent's name. I'm not sure, but I think that any threats of not allowing you to fly if you don't check in a carry-on bag are bogus. Because I don't think an airline can fly if a passenger's regular luggage is on the plane but the passenger isn't. They would have to get your luggage off and that would take hours, so are they really going to do that? I believe this because I remember on two occasions in years past when I was on a flight (in Europe) when a passenger didn't show up to board, that we all had to get off, our luggage was taken off the flight, and we each had to pick our luggage, which was then put back on the flight, and then the plane left, without the luggage of the person who didn't show up to board. Took another two hours. I have no good suggestions as to what to do if you have more equipment than will go into a carry-on, but certainly the most important items, like your camera, lenses and laptop, you should carry on even if you have to repack your bag at the gate or the door to the plane and hang the stuff around your neck and carry it in your hands.
Good luck with your upcoming fight with the airline. I hope you have a better outcome than I did.