I had similar situation but with L1B visa. My L1B expired when my I140 was still pending. I quit my job and used EAD from pending 140 with no issues. 140 was approved later following 485 approval. Your case looks even more secured

Don't. If I were you, I would stick with the H1B until you have a green card. We had the same situation. Our H1B from school expired in September 2023. We filed the I-485 on December 1, 2022. Our Priority Date (PD) is August 2022, and we were current at that time. Unfortunately, the visa bulletin was retrogressed after that. In February 2023, our school project ran out of funding. As a result, we had to look for an industrial job since the school hired staff in October for our major. We moved to another state to work, and one week after our employer ran our EAD, we saw the denial decision on USCIS's system. From the day I saw the denial on the system until the date I received the letter explaining the denial reason (it was two mistakes from the government. Firstly, our category is EB2NIW, but they treated it as E2. Since we were current when we submitted the I-485, our case would automatically be pending until it became current again if the visa bulletin was retrogressed, but they denied it); it took one week. After we realized it was clearly a mistake on their part, we went crazy trying to find a lawyer. However, most of them were too busy to respond or refused to take the case since there wasn't much to earn from solving this kind of problem. The denial letter indicated that we had left the country within 33 days from the date they made the decision. It mentioned no appeal, but we could request a reopening if we believed it was their mistake. Our new employer agreed to process the H1B. However, since our H1B is connected to the school and cannot be transferred to an industrial job, we had to wait for the 2024 lottery, which, as you know, was too late. Luckily, the company we work for is a global organization with its own legal team. They also have powerful legal partners, Fragomen. Both teams, totaling nine people, helped us complete the reopening request within 24 hours and submitted it to USCIS. A week and three days before the deadline, as we were about to leave the country, we contacted our congressman. He reviewed our case and decided to call USCIS (the office that denied our case). As a result, our case was reopened, and now CRP status. So, think carefully and imagine whether you will be as lucky as other people who use the EAD without any trouble, or if you'll be as lucky as us if you encounter the problem. Good luck with your decision.

Thanks, everyone.