I just went through this thread and made a few more donations to recently posted organizations.
People, if you want to receive coin give us your address!! You want to make it easy for people to send you public cash. This is total no brainer stuff.
A few of the organizations piped me to a website, asked me to pledge an amount in some odd unit I'm not familiar with, and made me mash the keyboard on fields that said "email" .. "address".. etc.. and to make matters worse it doesn't even look like it is the organization receiving the money because I saw links from coinbase, cavirtex, bitpay, etc.. who knows what fraction of any of that coin will make it to the intended recipient. Many times I have started down that kind of path and stopped. We have better things to do with our time and if the recipient doesn't have a clue what they are doing, probably your coin is better spent elsewhere.
I want to send you funds. Why are you messing with web forms and third party limited liability corporations? This is dead simple stuff.
Just thought I would report my experience. Bitcoin 100 team and charities, keep up the good work!
These 3rd party payment processors make it easier for organizations who don't fully understand bitcoin to still make use of the technology.
As to how much makes it to the charity, all 3 of those companies that you mentioned do a great job with that I think.
Coinbase charges 0% fees for all merchants on the first $1,000,000 in volume and 1% after that.
Bitpay is free forever unless you want advanced features like quickbooks tie ins.
CAVIRTEX is free for the first $100,000 in volume for all merchants and 0.5% after that. Charities are free forever.
I do agree the donations systems could be easier to use though.
The last charity that I posted,
http://giveamile.org/donate/ is using a pretty neat widget that I haven't seen before. I'm not sure if/when/where those BTC are being converted to fiat or at what cost though.