I don't generally run out of CPU, but having some go-to plugins available that use nearly zero CPU can be a good thing. And the plugins themselves are very good, on par or better than the other plugins I have. The two I'm most enthralled with are the 24/7 Limiting Amplifier (an LA2A vintage limiter knockoff), and the Megaverb. The former is great on individual sounds -- to make things grab their place in the mix. The latter is a full on high quality reverb. Since my normal mode of work is to compress everything (even if only a tiny bit) and always hang a reverb on a send, this puts the Powercore right in the middle of everything I do.
And the Powercore Element has enough DSP on it that you can run 8 tracks of EQ + Limiter and a Megaverb on an effect Bus without maxing it out. Pretty rad, imho.
The downsides? Well, this a a full length PCI card, which means that in my current case it couldn't fit at all if there were hard drives in the lower part of the card cage. Even with the drives moved out of the way, the last few millemeters of the card collided with the drive cage. I solved that by clamping vice grips on the drive cage and bending it out of the way. Ugly and low tech but that's how I roll. beats the hell out of buying a new case and moving everything into it.
The other downside is that on rare occasions in Sound Forge 9.0 I've had the computer reset -- go right back to the BIOS Boot Screen -- when I'm skipping around a file while playing back. This sort of 'poof' reboot has only one cause I know of -- insufficient power to the CPU. Sice I'm using a 5 year old 400W supply on a machine with a 65W CPU, 4 gig of RAM, five hard disks, a RME Hammerfall DSP card and the Powercore, it could well be that what I'm doing is causing a triple whammy of power draw.
But for $150 the Powercore was a steal. The current Powercores cards/firewire boxes are running about $900-1200. If you have a big enough case, I'd be on the lookout for a used Element.