Try out dualsense on gt7. Dualsense has way more strenght on the rumbles but you get the idea. Whats best is the constant rumble and the effect on grip levels under cornering, i hear DD does not have that and is more like a improved strenght rather than acrual rumble feedback.
I dont have really experience on DD's. Tried few hours on pc assetto corsa a year ago at nearby gaming place. It didnt strike me back then as anything special. It was some fanatec strapped to a motion rig.
If you got a tlcm and rim you enjoy (t300 is just fine rim), i would save on dd and get the tgr2 base only. I was in the same rabbid whole and all i found out mostly was "get dd same price yadayada" everywhere. Hate me people, but i vouche for tgt2 if you are already deep into TM eco system and sticking to gran turismo 7.
here are weekly races held with clean(drunk) driving2. If you really into gt7.
Now if you do sell your set for nice cash, then it might be good to get a DD. I believe its better for anything else but gt7. But i was happy with t300 already on everyhing else..
Tough. Flip a coin maybe?