Digitoxin, if you have more than one business customer web site on a CF license, Adobe claims that you are violating the "service bureau arrangement" of their perpetual license, section 2.6.4. It doesn't matter if your customer "doesn't have access to CF source code or have the ability to do development on their own sites". Also it doesn't matter if you are using Standard or Enterprise license. According to Adobe, you have to have one CF license for each business customer web site. Otherwise, they will push you to a custom contract which bypasses their reseller network and the price they quote you seems to be determined based on their estimate of your revenues.
I know it is hard to comprehend this. We had the same reaction so we requested a meeting with the CF Product Manager, Rakshith N., thinking this is one big misunderstanding. Rakshith was silent most of the meeting and he got off the phone in the middle of it so clearly he doesn't have much say on this. Someone named Abhishek from Account Management jumped in the call and try to reason with us by saying Adobe is losing potential revenue because if we were to put our customer web sites on-premise, each customer would have to buy a CF license. And our sales person said that he is converting many companies a week to this new custom license. If you haven't heard from them yet, you will.
Oh by the way, if I were you I wouldn't advertise that you have been using CF for so many years. When we mentioned Lucee, they blatantly threatened to sue us for past use if we don't sign their custom contract.
We are still in discussions with them. Will keep you posted.