This has been implemented as of Skuid 4.15.8 - it is now possible to specify, at a row level, whether or not to run default Lead/Case Assignment Rules, as well as (for Leads only) to specify a particular Assignment Rule to run (if you have multiple defined in your org).
Support for various other DMLOptions has been added as well.
See the release notes for Skuid 4.15.8 for more details (available from the Skuid releases page).
