The bottleneck for sync speed will be your internet bandwidth. Sync does not impose bandwidth limits unless you tell it to. To keep folders where you want them, you need to read and understand the help guides for setting up Sync and managing folders, and recognize that you want to start all clients in Disconnected mode (if you're using Pro). This will give you the opportunity to choose where to place each shared folder. As for reliability, there's no such thing as bug-free software, so you should continue to maintain backups of everything you consider important, and start out syncing a subset of your data to see how it goes before you go all-in.