@salmonkiller: Do you think the Shibata gyuto with its thin tip and blade stock can handle a pumpkin?
You can cut hard gourds with high hardness knives with acute bevels, but you'll want one that has a blade that is not too flexy. For Japanese gyutos, this means one that doesn't go too thin at the spine.
The issue with cutting pumpkins, butternut squash, acorn squash and the like is lateral torque on the knife. Because Japanese knives tend to be higher hardness, they are usually more brittle, and that combined with the acute edge bevel angle makes it more likely to chip at the edge from lateral torque when cutting something really hard.
I've cut hard gourds with these knives without damaging them. However, you have to pay attention to cut straight and not to try and steer the blade to avoid lateral stress on the edge. Many people prefer to use a "beater" knife like a Henckels or Wustoff for this type of task.
If your big thing is buying a set, it's hard to beat the ease of just picking up a nicer Henckels or Wustoff set with block.