There haven't been any major changes in Design Transfer in 7.6, but depending on which version you've tried it on before there may have been some fixes. You may want to take a look at Test To Live which is a fairly new component that compliments Design Transfer.
Test to Live is awesome. I would go that route. I was always acustom to using Design Transfer until I did a complete set up with a customer using Test to Live. Great addition to the Service Desk product by far.
That being said, I have done Design Transfers with 7.6 with no issues.
Can you help me with a tutorial video of how to do design transfer from TEST to LIVE ?