Sync uses adaptive uTP, so if there is any traffic it will reduce the speed of the transmission. We do work on improving the speed for 1:1 connection, stay tuned.
We are working on optimizing protocol further, so please wait for next builds. We will be faster. If the file is big, we transfer only one file in one connection. We are going to make in configurable. So transferring two files most likely will consume all bandwidth you have.
I am not sure that I get all the numbers. So you trying to synchronize two machines. Your uplink is 500Mbs download link for second machine is 50Mbs. You are sending 1G file. What speed you see? Yes, 1 connection per file is normal.
In a simple way, changes on recipient will not be propagated to other peers. It is very difficult to change file back, since it could lead to a very strange cases on recipient.
It is interesting use case. However this is first time users ask about such behavior. Do I understand correctly that you want a share, that will be emptied when all piers got the data? Complexity is that Sync doesn't know how many peers share the Secret. So if two peers got data, there might be a third peer that will come in few hours.
We don't like "security through obscurity" approach and will expose all details. We also understand importance of the implementation, so we will do something.
Sync has totally different goal, it is not about anonymity it is about privacy. Share your family pictures and movies across family members without need to expose them to employee of The Big Company.
Sync splits file to 4Mb chunks, if one chunk was changed - it will be transferred. It works well on files that doesn't change the size, for example TrueCrypt volume. If you add one byte in front of the file, all chunks will be shifted and Sync will not be able to detect shifted data.
Steps are following: 1. You need to find out your CPU type for NAS and download proper binaries; 2. Login to your NAS over SSH 3. Transfer binaries there 4. Unzip it 5. Made chmod +x ./btsync 6. Then in browser go to your_nas_ip:8888 and configure sync
We plan to do this, but not there yet. Consider this case, you share a file with a friend, we won't be able to give the ownership user name to the file, even if both platforms are Linux.