I think it's a good idea for the developer to get some money upfront. A developer might take time off their day job to complete the project. They're more likely to do that with some cash in hand. Perhaps that's solvable by them saying "I'm 1% done, please send half the pledge".
I'm just a developer/sysadmin guy who frequently has the task of spending money on behalf of the companies I work for, usually on contract. Occasionally the best available option is to sponsor development. In my case I've basically dealt with the open source developer as a private sub-contractor.
Which actually brings up an interesting point. For various reasons some companies won't want others to know they're sponsoring outside development. You should consider giving sponsors the option of having their pledge remain non-public. Maybe even anonymous to the developer, which is an interesting thought.
I'm just a developer/sysadmin guy who frequently has the task of spending money on behalf of the companies I work for, usually on contract. Occasionally the best available option is to sponsor development. In my case I've basically dealt with the open source developer as a private sub-contractor.
Which actually brings up an interesting point. For various reasons some companies won't want others to know they're sponsoring outside development. You should consider giving sponsors the option of having their pledge remain non-public. Maybe even anonymous to the developer, which is an interesting thought.