Hi!
I understand that “ramp” parameter is compound thus one is pretty complex. Its workflow slightly differs from other parameters workflow, for example you can not connect few “ramps” with expression. This parameter can be installed only from another node. Certainly it imposes restrictions on work with it.
But today I have found serious enough error. At creation of local parameters of any material on the geometry, “ramp” parameter is not overriden by them (http://img230.imageshack.us/img230/2916/rampz.jpg [img230.imageshack.us]).

Please see http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=15603 [sidefx.com] for bug submission guidelines, unless of course you're merely looking for community comments.