Need consultancy on strategy to deal with vendor msi's(repost)(repost)

What is in your experience the way you and your collegues approach vendor-msi's. In my company we are forced to work quickly and often I experience problem with using vendor msi's.? I know of company's that only use vendor msi's with good tranform-creation tools and that repackage al other applications to avoid problems. They state that they did not experience problems with software vendors that were not willing to deliver support afterwards when an msi was repackaged. Please provide your view on this issue.