Hi Julien.
When I started my a320 project, my first option was fslabs, because in a first contact, it is more visual friendly, easy to configure, it comes with virtual cabin, very detailed outside model...
But when I started reading in a lot of forums about its integration with cockpits and hardware, I noticed that it will be really hard, or impossible, because it is very similar to 737 pmdg in a first approach, but the data transfer with MobiFlight or other hardware it not as easy as pmdg, and the offsets are unknown for the moment, at least in my opinion. I heard about only you can read some parameters in a function called (rotor brake).
Another important aspect for me is how to undock windows. You can zoom in virtual cockpit (only pfd, nd, upper ecam, lower ecam), but when you change the view, all disapears... a lot of negative aspect to build a cockpit with fslabs at the moment...
I read in a forum that a fslabs professional version to cockpit builders will be available, and the data offsets, and a lot of improvements will be accesible. But when? nobody knows. Neither the cost.
For my, fslabs is an excellent option, (one of the best aircraft in the market for simulators) but for flying in your computer in virtual cockpit, no cockpit builders. At least for the moment...
For this reason I search for another option I and found jeehell. The begining was hard, very complex for me, when I started for the first time I was totally lost, but step by step, a lot of patience and reading user manual, a lot of forums... I'm starting to undestand the system, and believe me, this is a real software to build a home cockpit and full compatible with MobiFlight. All the inputs/outputs are published.
Maybe another forum users have more experience in fslabs, this is only my opinion.
Regards. Francisco.