I’m kind of a lighting nerd in my home. We have lots and lots of lights, all connected via a home automation system, and all use some sort of dimming to create “scenes”. I would love to save some power, but I have yet to find a “dimmable CFL” that dims anything like an incandescent. If you’re OK with just a little bit of dimming ability you’ll be fine, but you won’t be able to get much less than 30% without the light turning off completely.
With that said, I have not tried them with a dimmer exclusively made for CFL bulbs… but I have heard it doesn’t get much better.
The ones I’ve tried also hummed quite a bit while dimmed. Probably not a problem for a restaurant, but it was noticeable enough to potentially drive me crazy in my home.
I have not tried dimmable LED’s yet, and with the amount of lighting we have I wouldn’t make the investment yet anyway. Lutron makes a dimmer that is reported to allow LED dimming to 1%, but I don’t have much information on that. I think it was a fairly new product just a few months ago.