Hi everyone,
Thanks for all the answers.
I finally went for an Acer Nitro VG270UP which is 27in, 144hz, WQHD, g-sync compatible and IPS. I chose to keep my Benq since it's not very old and do a good job.
The Acer is bigger than I was looking for but I thought that I would move to another place one day and would be able to ditch my small desk.
But actually, 24in + 27in seems now too big for me and i'm still wondering if I will keep it or not. That's damn large. I feel like looking at a tennis game sometimes.
What I learnt :
144hz is a greaaaat improvement for gaming experience.
WQHD is really nice too for everything.
Can you give me a screenshot of how you use lightroom with dual screen ? I tried it for a few times but I wasn't more productive.