Bridging amps, Good idea or bad idea?

I own a Cambridge Audio 840W, which can be bridged, which makes each amp a 500w mono block as opposed to a 200w stereo amp. That's 1Kw PER CHANNEL! Are there any downsides to doing this? Will there be added distortion, or will it chnage the sound any negatively? I already high pass my speakers because I use a sub so they only get 80hz+ as it is.
The 840W is rated for 800W bridged into 4 ohms and the sub will help, particularly with an active xover. When you get close to the edge, even the wrong speaker cables can push it over. Depends on the speaker load... resistive, capacitive, impedance...

How about power? That's 2 X 2400W (at ear shattering levels), or 40A @ 120V.

Doubling and quadrupling isn't much of a absolute SPL increase but that's not what it's about. Closer to the point is whether that much power, without the low bass requirement, will benefit your speakers. I could understand for Maggies or Carver A3's.
The different times I tried it,I was disappointed with the results of the sound.Transparency,cleanliness,distortion, and changed frequency response just to name some of the drawbacks I encountered.
i was wondering the same thing myself . i had always heard that bridging was not a great idea but i have read that many users of the vac stereo amps that i am interested in trying : specifically the vac phi 300.1a and the vac phi 200 bridge them all the time . they apparently were designed to be bridged with a flip of a switch . i wondered if that makes these vac amps less than ideal when used in their monoblock mode . evidently the manufacturers don't believe there is any problem with bridging . still i wonder ...
The different times I tried it,I was disappointed with the results of the sound.
My experience exactly. Always preferred one of the amps alone in stereo as opposed to two of them bridged. Now biamping with two amps did seem to yield improvement. Of course you need an extra set of speaker cables.
If you search for on-line reviews of Spectron amp owners then, as far as I know, without exceptions - all states theat then they move from stereo mode to monoblock sound quality more then double.

I am also one of these. Spectron attribute this achievment to the proporly build power supplies most of all and high tolerance of its parts. Simon says that when you switch from stereo to mono - you hear practically distortion-free music.... I am not EE, will not argue techno stuff but I know what I hear. Improvments are STUNNING !!!!!!