I'm currently hard at work on book 7 for Mills and Boon and it uses the amnesia trope. I really wanted to write one of these books, because it actually happened to my parents.
My dad was in Malaysia, in the army and was driving a water truck through the jungle, when it overturned. He sustained a serious had injury and he woke up, he had no idea of who he was. A letter in his pocket, from my mum, was all they had to go on and my dad had to relearn everything, from his name, to who he was and what he did. He's 77 now and he never got any of his original memories back, so huge chunks of his childhood are lost, because he never remembered them.
The second project I'm writing, is a novel. I've got most of it plotted out and I've written about the first 20k words. The thing I'm sometimes finding hard, is that with this project, I have to remind myself, that I have the room and the opportunity to go in-depth. What I mean is, a M&B story has 50k words. Its very short and it has an intense focus on the hero/heroine. A novel can be 80-100k, so double that, therefore I have room for more backstory, more depth, more secondary characters. I can go deep. I can explore who these people are, I can find out more about them and share that, so that readers really 'get' who these characters are.
Both projects are really good fun and I enjoy swapping from one to the other. If I stall on one, I simple work on the other story for a bit and find that I can come back to the first one, with fresh ideas and a new perspective.