Ive flown RJ a couple times USA-Middle East/Asia when they had markedly cheaper flights than any OW or *A options, including TK or QR. The old A340s had more classic J seats but they went fully flat. They used to serve meals from the trolly so you can see and choose what you wanted a la carte. I found the aircraft always clean. I agree the crews tend to disappear. AMM as a connecting point was always fine for me - quick through security. I would mark the RJ lounge there as similar standards to AA Flagship Lounges. I also found on all my RJ flights I ended up having an empty seat next to me which was nice. If the price was right, I would fly them with the same expectations as AA or UA.