BAM can be easily used to calculate performance SLAs and provide this information to business owners, you can then enable BAM Alerting and use that for Monitoring your performance SLAs. If you also use the BAM API you will be able to extend this SLA monitoring capability outside the boundaries of BizTalk.
By defining an activity in BAM that collects at least two milestones you will be able to calculate the duration between them using a calculated field in BAM. Once this is done you now have access to the KPI you need to measure and you can create a query in BAM to identify instances where the duration was bigger than your defined threshold. You can also use BAM Alerts to receive a notification every time your query returns new results.
Read more on this topic BAM to Implement Service and SLA Monitoring