I'm not sure what you're getting at with 1- I don't think any service ever can transfer files to a machine that isn't on. As soon as the co-worker shows up on Monday, the transfer will finish.
As far as 2 is concerned though, that is not the case. Don't forget, it's built on top of BT. As each piece of the file gets transferred to other clients by the original machine, the other clients will be able to send those pieces out too. In theory it will be faster than a transfer from a central server.
1-Actually Dropbox lets everyone do just that, I can access the shared folder via the dropbox website whenever I want, download files in there and even access the old or deleted versions..something I see very unlikely in this case for now
Oh I see what you're saying. Bottom line, there needs to be at least 1 copy of each piece available to pull. It also definitely lacks a lot of the features that Dropbox provides on top of file syncing.
As far as 2 is concerned though, that is not the case. Don't forget, it's built on top of BT. As each piece of the file gets transferred to other clients by the original machine, the other clients will be able to send those pieces out too. In theory it will be faster than a transfer from a central server.