With any lamp other than incandescents, the lamp manufacturer is the source for definitive information. As far as I know, dimmable fluorescents of any type require a dimmer specific to that lamp. Some LEDs specify that they are not dimmable. I have some LEDs that are marked dimmable and they are doing well with a regular dimmer of recent manufacture. Extremely old dimmers may not be the correct type.
And multi-switch circuits such as 3-way and 4-way must use ONLY one dimmer.

thanks..seams the tech in these new dimmers is relatively new...unles I get posts to the contrary I think it prudent to stick with a regular dimmer and regular bulbs until the LEDs come down in price.

I'm using Philips dimmable CFL R40 floods with 13-year-old Maestro dimmers, with no buzzing or other problems. The CFL's can't dim as low as incandescents, rather they shut off below some point.

Electronic dimmers, some of them anyway, must have a minimum wattage connected to them in order to work properly. Hasn't been an issue in my case because the dimmers are handling four floods, so the total wattage is over 100. I would guess that the special dimmers have a lower minimum wattage compared to regular dimmers.

You can dim from multiple locations with special dimmers like Maestro. After 13 years, no one in the house but me has been able to completely understand how to operate them, so I wouldn't recommend them.