Hi Aaron,
I previously worked in a company where we had nearly 3000 data-driven tests running in over 40 test suites. The actual test cases in SoapUI were around 400 or so, we re-used the same test cases to test various scenarios i.e a test case is to login, getProfile, verifyExpected and actual, fill out report, clear relevent properties and run the same test again with different data-set, i.e login with superUser, admin or employee etc.
You can re-use the same tests with data-driven approach to test various combinations. The practice you have described seems pretty decent, though I would add reporting/tests outcome in there to know what scenario/data-set passed or failed.
In automation, the key thing is to re-use as much as possible. We don't have an option of step defs in SoapUI, though we can use the concept of step defs within our test cases.
Strongly agree with Radford in regards to ensure the test cases can be run independently. They should not depend on previous steps to pass or generate data. In future, if your regression pack beocme very large, it can be managed by splitting the XMLs in two or three and run them in paralell to save time and to ensure all tests will still pass as there is no dependency.
