With 1703, the partition type problem of MBR to GPT is solved, but all changes are still not possible out of the box. The included tools like diskpart only support shrinking or expanding a partition, but not merging or moving a partition or converting it from logical to extended or vice versa. So if you opted for a different disk layout involving such kinds of changes together with the new OS, you need to create the new structure before or after the upgrade with third-party tools or go with the classic wipe and load option.