Hi,
I'm using KVM available in AMT version 6.0.30-build 1203 through TightVNCViewer, RealVNC Viewer Plus, and Intel commander tool
I'm facing following issues in KVM
1. If OS restarts, KVM connection got disconnected. It's not stable, sometime able to see the restart process, sometimes disconnected message. In AMT 7.0 version there is no problem with OS restart
2. In AMT SDK it is mentioned
The KVM feature supports gaming and signage platforms that have high-resolution graphics (1920x1080 with 16 bits of color depth).

Once I do connect the monitor cable the missing visual appears instantly.
I do can access the BIOS and GRUB with kvm-over-ip, so might be a (Debian) Linux only issue.