I do not have Turn 5 experience, but I have both a SCH and WHM who are relatively close in gear - SCH is my main, so it's gear is better and the gear they share is more tailored to SCH BiS, but...

I enjoy healing as both. I've done most end game content (except turn 5, so I guess that invalidates my opinion for some people) as both, and what it basically comes down to is I have a different healing role depending on which class I'm playing.

IMO, if people think that the WHM is gimped compared to the SCH, it's because they are trying to play the SCH's role with their WHM. And vice versa.