Wayne has a blog post out there about eBridge integration between MAS90 and Salesforce.com. eBridge's ""integration"" with MAS scares me. They use the ProvideX R/W ODBC driver to push things into MAS. I had a client who tried for 9 months (unsuccessfully) to integrate MAS90 with eBay stores using eBridge, and they eventually went back to QuickBooks.
I like Salesforce.com, but they are really expensive, and it is a real pain to cancel. I used it once in a prior life, so I'm not just saying that.
If they like the subscription model, Sage's subscription model is a lot easier to get out of than Salesforce.com, and the integration would be a lot tighter.