I finally have sufficient HDDs to transfer over backups. Can I change from mbr to gpt on two of the drives to avoid transferring 5GB of data just to change the disc to gpt, without any data corruption ...

Does anyone know if it's safe to run the Windows 10 "mbr2gpt.exe" tool on a (non-OS) disk in Server 2008 R2? If so, is the process reasonably quick? (This is an almost completely full, 2.0 TB disk.) ...

Many high-end games, professional software, and cloud security applications now require Secure Boot and TPM 2.0 features, which are only supported when the system disk uses the GPT partition format.