I also don’t use a FPS counter, but I could definitely tell with my eyes that something was off FPS-wise. Even cruising at FL380 it was stuttering when I’m not even near the ground or any clouds that high.
Also, the FBW mod is more so a “study level” aircraft model as others have called it. I’m definitely not a casual simmer, since I fly everyday. However, at the same time, I personally just didn’t need all the extra enabled functions and switches the FBW mod has. I just enjoy flying from point A to point B, cold and dark from the gate and all and making it feel as realistic as possible. Heck, I don’t even use the AP as you would IRL, but still I get that very realistic experience even with just the default A320.
So many people on here were always complaining about the issues and bugs they had with the default and I didn’t understand because I never had any issues until the USA update of course. I think it’s just your taste, if you want an ultra realistic, fully functional, “study level” FBW mod, go for it. If you can get by using the simplified, “vanilla” default A320 like me, also perfectly fine. And like I said, having a very smooth graphics performance is much more important to me than a realistic aircraft with FPS drops and stutters. Again, just different tastes and priorities.