Hmmmm
I don't have these issues, I have the AMI with Tune2Air WMa3000. Occasional I have had connectivity issues particularly if I stop the car briefly and then start it again after being in a
Shop. It seems if you go through the 'normal steps of starting the car (unlock, get in, start) it connects but does sometimes get confused. That seems to be Bluetooth technology though. It's not enough for me to not use it or find it irritating.
The sound quality is excellent and the functionality from iMusic from the RNSE2 is great. For Spotify I have to select music from the phone but that's to be expected, it's the iPhone cable designed for iPhones.
The AMI can be installed along side the CD changer however they both sit in the same part of the glove box. You would need to leave the CD changer where it is and bring the AMI cable into the glovebox from behind, You couldn't use the whole AMI box but that's no big deal.
Regarding the Kufatec vs the OEM connection, you are correct the Kufatec interfaces with the existing quadlock, this is not an issue but not how it is done form factory. Also if you were to add later a Kufatec harness for say Bluetooth, you could end up with a quadlock plugged into another quadlock and then the oem quadlock. Again nothing wrong with this and it will function but looks a little messy if you're a purist.