If a utensil is safe for a ‘normal’ microwave, is it also safe for a flatbed microwave

This really should be a comment, as it doesn't directly answer the question, but it's kinda long ...

I do the same thing, but I'll admit there are a couple of disadvantages:

1. When you stir-fry, you will aresolize oils which will end up depositing on the utensils (and pot racks above your stove).
2. Some things will splatter (eg, a long-simmering tomato sauce), which again means the need to wash the utensils.

As for the degredation issues -- if they can't even handle the temperature of steaming, you probably don't want them in the kitchen at all. I haven't notice any problems with my wooden or wood-handled utensils.

I don't have any better space, as my cabinets are so low that hanging utensils can't really fit anywhere else in the kitchen, and I find hanging so much more convenient than everything in a drawer or a container on the counter that I'm not willing to switch.

Are there safety issues? Maybe if there were a fire on the stove, but so long as it isn't the fire extinguisher being stored there, I don't think it's that big of an issue. (that's not to say that I know for sure there aren't any ... I just don't know of any)

Here is a set of guidelines I found from a major manufacturer: http://www.geappliances.com/search/fast/infobase/10001216.htm

As you mention, any metal items or items with embedded metal are not appropriate. Thinner and bendable plastics are probably not a great idea either since they can melt. Most ceramics and glass should be okay.

When in doubt, check to see whether the item is labelled as microwave-safe, and if you can't tell, test it first using the method described in the linked guidelines.