i guess both are useful, depends on what your goal and expectation is.

Speed oven is a microwave/ convection oven combo. Microwave generally heats up the center of the food much faster and the oven part heats up the outside, so food are cook much faster. However, microwave doesn't cook very evenly, and it's not known for retaining great flavor, and tends to dehydrate food unevenly. Also. there is also a health concern with microwave itself and food losing nutrients.

Steam/convection oven combo is not going to be as fast as a speed oven. Also, there are somethings only microwave can do (i.e. popcorn). Steam alone is gentle to the food and known to retain most nutrients and flavor of the food. Seafood is great for steaming. It's great for reheating dishes too and it will not have a "dry leftover" taste from microwave. When combine with convection oven, you can roast meat or bake with lots of moisture. You can also use it to reheat leftover bread to make them soft again.

In your examples, both ovens will do the jobs, speed oven will be faster but I think steam combi will give you better result.

This post was edited by noopd on Tue, Jun 11, 13 at 23:31

I baked 2 giant potatoes in my speed oven in 9 minutes and they were awesome. The skins were crispy and the insides were done perfectly. Another time, I made a giant sweet potato (or yam) and my husband loved it.
The speed oven sounds complicated but just use common sense.
You program bottom heat, top heat(think browning), microwave concentration (a little or a lot) and convection.
Reheat is a snap with the moisture sensor. Yesterday, I reheated sword fish and it came out perfect. (Microwave only)
Pizza reheat is amazing- crispy crust and not all chewy and soggy. (Speed function)
One of my favorites- Zingermans or achaatz pot pies which take an hour plus to bake- 20 minutes with a golden brown (speed function)

A speed oven is a microwave on steroids.
You can just microwave
Bake- although I use my full size oven for most baking. I do use to bake casseroles.
Speed- described above
Warm- keep food warm- I even used this function as a "crock pot" I forgot to bake the bread and needed the oven space- so put on keep warm high whole the bread baked.
There are other functions but I haven't tried them
Btw - I guess you can tell that I like my 240 Advantium.

I can't tell you about steam as I don't have one.