Funny coincidence. Hilary is working on a new version of qRules 2.0 that supports this exact scenario - all client side. We should have that out in 3-4 weeks. Do you want to beta test it? Send me e-mail.
qRules 2.0 will support mapping a form on submit to one or more SharePoint lists. It will also pull from those lists on open (if configured that way).
InfoPath 2010 also provides support for creating forms from lists and mapping to lists. The support is limited to simple list-like XML structures.
In the meantime, we have another tool that supports batch mapping XML to SharePoint lists - here's a link. As a DBXL customer, we can provide a free copy of this tool to you. Just let me know if it will work for your scenario and we'll send you the tool.