Just talked to our QA team. There should be no issues, but keep in mind these things that could affect your backup job:
1. Guest OS VSS snapshots creation (if they are scheduled) should not overlap with your backup job
2. You need to monitor the diff area
size (VSS storage location), cause if you run out of free space for your diff area, VSS snapshots might be dropped/consolidated.
Other than these two, you should be ok doing backup jobs without VM suspension task.