That really just depends on what the number is. Assuming that the added dps from either is 300-600 effectively, all the WHM would need to do is be capable of dealing that increased amount on their own. Or more. So a WHM that can deal that much more in comparison to their cohealer would be good. Say, AST with the second highest dps does 2k on average, while a WHM does 3000 on average. That's a 1k added dps bonus over the AST's 600(assumed) average added contribution through cards, and WHM could substitute for an AST when dependable damage dealing is needed rather than an unreliable dps buff that may never appear.

I mean. It's just common sense... that seems to be the niche they're trying to push WHM into, like SAM.