Ultralinear and Triode. What's the difference

The way I hear it on my Cary SLI-80 is that the triode mode is softer, with less frequency extension, the edges are rounded off, the midrange is slighty more pronounced, less bass control and other things related to those issues. I like UL on most music truthfully, but some others like only the triode. Of course, whether you like one or the other has to do with you, your room, and your other equipment. Are you thinking of a specific piece of equipment? Maybe someone can chime in that actually has one?
Rush

Looking at the newer Primaluna integrated amps, there's an option for switching between modes on the fly. Just wondering if it's worth the upgrade.