I upgraded my installation to CUM 15 last year. CUM 16 was available at the time, and has some nice things like Employee Self-Service module. We tried using the web enablement, and found that it was not the best interface.
Also, if you have any video's modified - adding fields in the DDS or otherwise using non-stock video's, the web translator does not do a good job of dynamically transforming the video's in the CUM unless you have purchased the tool from Oracle that allows you to do so. The price for the tool is not cheap and we had not budgeted for it.
When we discovered that, we held off on moving to CUM 16 or working with the web interface as we have a few modifications that would be impacted.
We have also noticed some video's in CUM 15 behaving with unexpected results if you use the WorldVision product for your interface. Green screen seems to be fine.