488 vs. 296?

I'm rather certain that you won't miss your 488 on track vs. a 296. I've also driven the 296 and have an F8 (and go to the track frequently). I have no complaints about the acceleration in the 296. Also, considering that the 296 laps a short track like Fiorano half a second faster than a Pista, and a full second and a half more than a 488 GTB, I'd think you'd be ok.

 

7 flat Pista at the ring. i'd venture to say the 296 will do it in 6:55. same as 765LT and GT3 RS

 

Acceleration is better than the 488, which is no surprise considering the power advantage for the 296.
To get the best acceleration it's still useful to use the right gear ratio (which may not come naturally given the initial feeling of huge torque at low rev).
When I drove the 296 at my "local" track of Val de Vienne it was about 10 kph faster everywhere than my 488, without pushing (that was my first contact with the 296, so I was not as confident as with my own car).
The cornering ability is more impressive than the acceleration IMHO - whereas the straight line speed is expected, the fact that it's not slipping at all in the turns in spite of higher speeds and a weight penalty is really astonishing (I do not know how much the newer generation tyres help, but it's impressive anyway).
The only (slightly, after all) disturbing fact is some instability under hard braking, that I first experienced at Val de Vienne and confirmed at Varano. Not sure how the shorter wheelbase and the suspension set-up contribute to it, but it's definitely noticeable compared to the indefectible stability of the 488.
If you look at the youtube thread about the 296 there are a few on-track videos (including mine from Varano )