I had a first real look and play with iracing at he weekend on a mate's machine and I have to say I fell in love with it.
The points you've highlighted are indeed the biggies.
The safety rating system is so simple yet genius and means you'll get much more careful driving at all times.
The physics are streets ahead of LFS - no more to be said really.
Real Tracks & Cars - I think the LFS cars are great so for me it would just be having the real tracks that would make all the difference - this is something the LFS devs could do relatively painlessly as well.
The serious downside however for some users will be the cost. However for anyone earning a good wage it's pretty cheap still.
I won't be subscribing just yet as I'm not expecting to have much spare time over the next couple of years but when I am ready to get back into sims in a big way as it stands currently I'd be signing up to Iracing. I hope LFS improves in the meantime.