Yikes - it's quite a sentence. What is dangling is that who assessed the performance should immiately follow that clause.
In a shorter form:
Having assessed the performance of MS SSIS, I have (or the team has, etc.) determined...
Here's another suggestion:
I have/The team has/We have assessed the performance of Microsoft SQL Server Integration Services (MS SSIS) in integrating data from disparate sources in the NL Cognos system, and I/we/they have determined that MSS SSIS should be adequate for our needs.