A lot of CIs, myself included, are in the same position. I was originally taught how to program Marantz (Pronto) Remotes and not quite two years ago changed over to RTI and haven't looked back since.
Occasionally I am put in a position where either an existing, but usually a new customer, has bought (maybe a better way to put it, has been sold) a URC or Harmony remote and wants me to program it. In the past, whenever this happens, it invariably turns into a disaster and usually ends up costing me time (money!).
In the future the answer will be a straight out NO. (HiFiRobbie, make sure I stick to this one!)
The analogy I will use is that if the customer owns PCs and has an IT guy who services them, and all of a sudden the customer goes out and buys a MAC, because the salesman says 'They're really good and anyone can set it up'. The Microsoft Engineer doesn't have the time nor the inclination to learn all the intricacies of an Apple Mac set up. Not that I would normally be so blunt to say (to the customer) that if the salesman says it's so easy, let them do it!