Agreed, we never run the 24mm, even had a 22mm on the demo car more than enough. Rear ARB is the one you need as our little ones don't have them as standard due to rear fixed axle.
It's all a careful balance but luckily people like me have done all the leg work so you don't have too. Regardless a little more understeer is easy to manage, FWD are a doddle to drive on the limit, 4WD and RWD whole new ball game.
Ideally I would never want a FWD car with oversteer but everyone will be different. Oversteer on Starlets is usually attributed to mis aligned rear axles (not running an adjustable panhard rod or having one that isn't setup properly), no rear brace, not having a roll cage, no rear ARB, poorly selected shock bound/rebound/spring rates etc etc, the floor plans are also really thin, hell it was a town car not a racing car Toyota didn't intend it to be but that can all be changed with some little head work
If you want a true track monster roll cage is essential, not for safety but merely to stiffen the chassis, the more points the better and imo front strut triangulation bars are essential to make it all one complete frame otherwise you get excessive flex. Regardless a simple bolt in will make the world of difference you just need to way up what the car will be used for, what you want and what the overall outcome will be. For some a roll cage just isn't practical but everyone will have different needs.
You either make compromises for practicality and comfort with the loss of a little handling, or you go all out, no messing and make it as good as you can impossible to have the best of both worlds.
T