I use an ECE scrub (actually a converted smoother) the curved Chrome Vanadium cutting iron holds it's edge forever, especially when sharpened a bit steeper than normal for maximum edge retention. A thicker iron would be nice but the standard one works fine.
The thing with scrubs is that they are used across the grain, in this direction the timber is much weaker so there is less demand on the cutting edge and the user. You'll never get any sort of finish, but for changing the shape quickly it's like having a switch to turn ash into pine and back again.
It's easy to make the mistake of obsessing about all planes to the extent that you would a smoother. A scrub is completely the opposite end of the spectrum, an adze with a fence, nothing more.
It should be cheap, brutal, flat to within 1/8 of an inch and have a blade that gets sharpened on an annual basis. I wouldn't even hone the iron, just use it straight off the grinder.