Over the past few months I have been getting interested in monolight strobes. Although I have done quite a bit of reading and spec comparison, I find myself confused more often than not. To begin with, I started out looking at output of various models and comparing them to my speed lights, specifically my 580 exII. So now, I have a few questions, but first some background info:

I am most interested in outdoor use. Though none of the strobes I have looked at have the fast flash durations I need for Hummingbird Photography, I am thinking they may be more useful (powerful) for other outdoor applications--i.e. being able to use an umbrella/beauty dish etc without having it three feet from my subject/s-----Most of my subjects would be birds, pets, wildlife and occasional people photos----note, I don't mind running a long cord for power or even using a generator if neccessary.

1. The 580 ex II has a guide number of 190 when set to 105mm, this seems to be about the same output as a 400 watt/sec monolight----but there are large variances in the guide numbers between different brands and different models of monolights when they are all advertising 400 Watt/s----What am I missing?, Is there a better way to judge power output for monolights.

2. The less expensive monolights like Impact and Sunpak seem to offer similar features as the more expensive lights---so what's the catch----what should I look out for in the less expensive lights---or--what should I be willing to pay for in the more expensive lights?

3. Finally, what are some good/reputable brand names when talking monolights, but ones that won't break the bank?

Thanks for any info you can provide.

Bob