I have them taken out (road trip with my car, we slept in it some of the nights). I will weigh them when i get home, but it's certainly no more than 40kgs, I took them out by myself, and got them in my flat, taking the stairs. Spare wheel+jack another 10kgs max, so even if you take all the unnecessary bits out, you are still at a max saving of 50kgs, which unless you go to a track to race is irrelevant.
There is increased noise, but the car is completely covered in carpet, so the only metal bits showing will be the hinges. It's not very bad unless you are on wet roads, and even then it differs between different tires. On dry roads it's not unbearable, I've been driving like this for two weeks on Firestones. I had it out before (to cut the hinges to allow for greater adjustment range) and i had some winter Pirrellis then and it was bad, lots of noise from the tires then.
Also, anything in the boot will come flying forward when you brake, a very dangerous thing, even if you only have small light things, they can still find their way under the pedals etc.
I did not feel a change in car behavior, the weight difference is much too small, and I've taken the car on a set of very demanding roads these past couple of weeks. It's nice to have a decent sized boot for a change, without the backseat it's almost as big as my friend's V40
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