Pull syncing wouldn't use any more bandwidth then "push" syncing. As I mentioned, the only downside is the upload speed for most ISPs is much worse then their download speeds. However, you have this same problem with push syncing. The only difference is that for push syncing, by the time you need it, it's most likely already been pushed up, and then down again.
I mentioned two things that solve for this:
1. Local network syncing. Much of my syncing occurs between my desktop and my laptop. Syncing shouldn't require an outbound connection (send up to dropbox, send down from dropbox).
2. Beyond large media files, most files people want to sync are still fast on high speed internet. Most pictures and documents aren't large enough to be a concern.
Finally, while most people's internet connections might be lousy, then they will suffer with the syncing regardless of the method used.
So yes, I do realize upload speeds are an issue, but it's not a big problem.
I think that "only difference" you mention is pretty crucial given the limitations we're talking about. If it's sync-on-save, then it's syncing while I'm doing other stuff. If it's sync-on-read, then it has to sync when I need the file, which can take a nontrivial amount of time. Looking at my desktop right now (which is just random stuff I happen to have received in the past couple of days — pictures grabbed off cameras, files emailed to me, etc.), I see that 10% of the individual files are over 10 MB and 25% are 1 MB or more. My browser's icon cache takes about 10 MB. Firefox itself is 53 MB. That's a heck of a launch time at 14 KB/s. A 1 MB file on my home computer would take more than a minute to open at work even if I use 100% of my home upstream.
> I think that "only difference" you mention is pretty crucial given the limitations we're talking about
Yes, it's a problem. A problem I talked about in the original post. However, it's temporary problem, and only for people that have to suffer with slow internet. For these people, even download speeds are horrible. Steam, for example, as wonderful as it is, is hated in places where download speeds suffer.
However, global internet speeds are increasing.
For me, I can stream my music and videos from my home to work. While I don't for a moment hide behind this problem, I won't pretend it's a road block.
Simply put: it's a problem as much as people without internet wouldn't be able to use it either. Enough people can use it that it would be useful.
I mentioned two things that solve for this:
1. Local network syncing. Much of my syncing occurs between my desktop and my laptop. Syncing shouldn't require an outbound connection (send up to dropbox, send down from dropbox).
2. Beyond large media files, most files people want to sync are still fast on high speed internet. Most pictures and documents aren't large enough to be a concern.
Finally, while most people's internet connections might be lousy, then they will suffer with the syncing regardless of the method used.
So yes, I do realize upload speeds are an issue, but it's not a big problem.