Wow - a big change is around the corner for you and your family! I applaud your recognition of this and appreciate the anxiety you must be experiencing.
Knowing what I know about having diabetes in college, were I in your place I would get the CGM ASAP. Like now. This would offer time for your son to get used to the device. It is still a little cumbersome because it requires 2 different devices if he uses a pump. However, I received VERY promising word from a friend with connections at Animas - the Dexcom and Animas and presumably the Dexcom and OmniPod will be communicating very soon. They suspected January. That is terrific news for all of us "real simple" folks who yearn for a day when we can care just one contraption to control our diabetes! But alas, I'm getting ahead of myself. . .
There are many risks in college to a person with diabetes - the biggest of which are alcohol and no adult supervision. Low blood sugars make people seem drunk at times and most other new or not-quite-there adults rarely appreciate the reality that their friend may be in trouble and that's why he/she seems groggy or is passed out. I don't write this to scare you but I knew several other people with diabetes and this experience was pretty universal. That being said, the Dexcom will be your son's lifeline 99% of the time.
Yes, it can be a bit of a pain figuring out how to get it to work and there is definitely a learning curve. BUT - the learning curve is typically 3 months - and that gives you more than enough time for him to figure it out before taking the next step. Moreover, its not that difficult to manage (I started in my 3rd year. . . the most difficult year. . .of medical school). I have no reservations about recommending that you, along with all other parents of soon-to-be or current college students with diabetes . . . CGM can make a huge difference. Not only will your son be in charge of his own schedule, eating, exercise, life, but when he wants to come visit you, an unrecognized low can be devastating. The number one cause of death for a young diabetic older than 16 is automobile accident. The Dexcom can help tremendously - check the number as he drives then pull over if it alerts.
Bottom line - I highly recommend that you take the plunge now. As parents, we can't find enough safety nets and I know that this might also give you some peace of mind. Furthermore, I would encourage that you look at Animas Ping for your replacement pump ($200 if your insurance doesn't cover it - you just have to return you Cozmo to them) since there will be an integrated system to which you can upgrade in the near future. I think this can make a tremendous difference and strongly feel that every endo should be prescribing CGM for the new collegiate diabetics. Feel free to ask any other questions you may have - about Dexcom, college with diabetes, etc.