I used SQL to something similar integrating our CRM product with Dynamics, Outlook and our plant production system. If you know SQL, things are not that bad. Finding data in Dynamics though often is a pain --- I had to get a shovel and dig to find some things that were not documented too well.
My applications are all triggers, stored procedures, custom views & DTS that I installed onto our Dynamics databases to pull the info one way or the other. I also push things to a reporting db for my intranet reporting.
Quite complex (check)