Well, it's not 'a good and valid indicator' if it pulls me off the sight line, which it wouldn't do in reality. Sure, we can't feel G in the sim - but that is definitely not going to change now, is it?
We've already got the ridiculous creaking and groaning of the airframe to tell us 'Hey, I'm pulling G!'. In my experience (admittedly limited with higher G's or aerobatics, but still there), apart from feeling high G in aircraft, you can kind of hear how the aircraft is 'biting' into the airflow more, and you get noises of buffeting more than any creaking. But hey, some kind of harmless feedback helps some people I suppose....To me, having the stick in my stomach at 350km/h+ should tell me something
I actually turned off headshake when I first got the sim, it's just so unlike real life flying. It's better now, but still has stupid parts (the sinking into the pit, and cannon pummeling as mentioned)