Design best practice : put state-independent methods on class side?

I have some methods that currently refer to iVars, called from other methods 
of the same class. I need similar functionality in other classes, not 
related by inheritance, and want to keep it DRY.

If I move the iVar references into explicit method args they can be easily 
re-located and shared.

Is it then good or bad practice to take a such collection of related 
state-independent methods (they don't depend on any iVar) and put them on 
the class-side of some suitable class?

My options and concerns:
- I could move them up the hierarchy on the instance side but sometimes hit 
single inheritance limits
- I could use traits for these but am unclear about the future of traits in 
Squeak
- I can put on the class side and call easily from instance-side methods, 
but is this OK practice?

Thanks,

Sophie