I guess the ramp up generator if you think about it just controls the rate at which SOAPUI test cases are launched. I suppose it depends on what those users are doing in their own little worlds. If they are just executing one test after another (not concurrently) and the load aspect comes in when you introduce multiple users then all you are really talking about is ramping up the number of requests over the course of 8mins 20 secs to a maximum value of 100 concurrent requests. Admittedly with the ramp generator you can only say x requests per y seconds which isn't quite the same. I guess what you really need is a graded fixed load generator so you can change the load incrementally every y seconds. Difficult one!!