I have not had any experience with using RSSBus. At my organization, we went with DBAmp and I built my packages to work around that. It uses a linked server and it's own API to query and sync the data with SalesForce.
The package I developed keeps a local copy of the pertinent tables synchronized with SalesForce every 4 hours. Some tables are updated more often based on specific needs. The only time there are issues is when the schema is changed on a table. When this occurs, I have to schedule a full pull down of the table to capture the changes. The package will still continue to run and capture changes to the data but ignore the schema changes until the full pull down of the table occurs.
If anyone else has had experiences with other tools, I'd like to hear about them.