Sounds good to me Thermal..
We don't see much piece work over here, the norm is a flat hourly rate with a guaranteed minimum amount of hours paid and an overtime rate for any hours beyond that (x1.5 for weekdays and Saturdays, x2 fro Sundays, x2 + day in lieu for Bank Holidays, kind of thing).
As you say, at least you know the minimum guaranteed wage you'll be getting every week.
