Since US deliveries of LFP SR+ vehicles didnt start till this year, you must be talking about internationally, where they started last year. In any case, whether 1/2 a second is "a little or a lot" is going to depend on individual experiences, what people are used to, etc. a 5.8 second model 3 is going to feel fast to someone used to econoboxes, while its going to feel extremely slow to someone coming from a 2018 Tesla AWD Long range vehicle.
The LR AWD Model 3 (with or without accelerator boost) feels "slower" to me, if I am flooring it from a stop, since I have a performance model 3. My wifes X3 M40I used to feel fast to me until I got my Model 3 performance, now it feels unbelievably slow.
If it were me, I would not buy one of the LFP rear wheel drive Model 3s, because the fact you can charge it to 100% all the time means nothing to me ( I dont drive the entire range of the car out daily, so it doesnt matter that I can or cant charge to 100%) yet you feel the cars acceleration every time you step on the pedal.
I would buy the LR AWD myself, as that feels to me like the sweet spot between performance and price. 1/2 a second is a fairly substantial difference, to me, but to some others, they would rather charge to 100% all the time, or they dont care about the acceleration.