What's your experience with Lane Departure assist and adaptive cruise control

I am in the market for my first ever Lexus and I am looking at 2017-2019 GX.When watching reviews of the vehicle I seem to be getting mixed reviews of the two systems. Most of the vehicles I am looking at in the Luxury trim does not come with those systems. Is is worth in your opinion to push to get those features?

As a secondary question. I am mostly looking at vehicles with around 70K miles for around $35K is it worth saving about $5k to buy one with 100K miles?