yes , almost. Like the VTEC system of Honda: don't use much gas when it's not needed, but still be powerfull if you need it.
rmclock monitors cpu load and as such you can have both worlds. Run very cool and lowspeed when you don't need the power, and have a very powerfull system when you need it.
My cpu runs at 30 deg celcius max when surfing/typing/... and rmclock kicks in and pushes the cpu full speed when compiling,... (al the way up to 45 deg celcius)
Why do you need to make a choice between cool and powerfull. Why should I put up with a overheated pc because I need that power only < 5% of the time?