More Power than 580, More Portable than Studio Strobes

I do mostly weddings, some portraits. I like my 580's, but there are times when shooting in full sun that they're simply inadequate.

Knowing that I need to move and react quickly, I'm not inclined to get a set of Rangers with battery packs or something like that. What I'm looking for is something that fits in the gap between the two; quite a bit more power, but hopefully something that is still not too heavy, too bulky, or requires too much set up time.

I've been looking at maybe the 400 w/s QFlash, which I know is not enough to over power the sun, but it offers a considerable improvement over 580's. Are there other similar high-powered speedlights I should be thinking about?

The Qflash t5dr is a good system. It requires a flash bracket and overall is considerably more bulky. I am used to the weight and do like it's features. Even in larger events, I do not run out of power. But it is pricey, especially if you want to get multiple set ups. I have never tried the higher end Metz, which also have lots of power and have external battery packs. Perhaps others will offer info on the Metz.

Metz 76 is more powerful than the Canon 580
Metz 45 is more powerful than the Canon 580, but its angle of coverage is fixed at 35mm lens coverage angle (not a zoom head)
The Quantum mentioned earlier is more powerful than the Canon 580

If you don't need ETTL, you could look at Lumedyne. 200Ws or 400Ws, up to 3200Ws with booster.

In line with not needing ETTL, you might want to look into the Norman A400B which is a 400 w/s portable unit which has fast recycling between flashes.

And, indeed, I'm working in M nearly all the time.