Well for me the G25 wheel get more loose in my hands but that is because the thin grip. The 911 wheel never slip for me but 100 % force feedback no way in most of the games I run. It gets nnnnngggh in high speed corners and really affect your lap times after doing more then 3 consecutive laps. And yes you can feel it the day after. G25 is less fatiguing for sure. I have a hard time tuning down the force feedback as much as I should lol. So 66 % and force feedback in game at about 80 % generally. This differs of course for different mods and sims.
For Race 07 I have steering force at 130 for G25 and about 80 for the fanatec wheel. Force feedback 100 % on G25 and 80 % on 911 wheel. (However max force feedback is 150 % lol on G25.
For me the force feedback strength above what you can use doesn´t matter.
As for hitting curbs for these affects the G25 seem to be a bit faster and stronger. But again don´t know if it because my grip isn´t as good with that wheel I have trouble parrying it
. I guess the dual motors change directions faster so that type of force feedback the G25 does good. Resembles exactly what I feel with my bass shakers. Not that I care to much about those effects when I get my cockpit with buttkicker LFE running I will probably disable those effects on my wheel since I rather get them directly through my body