potatoes are actually very healthy for you... the problem is people fry them and eat too many of them.... but a small baked potato withe a little olive oil and some fresh rosemary as part of a complete meal is a great way to get veggies into your diet.
Potatoes are a good source for glycogen which you need for the quick fix to exhaustion while working out and the energy is not stored as fat. I think your use of canola oil to spiffy up the taste is an excellent way to do that as there are some health benefits you can derive from it as well. Potatoes are also a good way to keep your cholesterol and triglycerides in check because of the fiber. However, I do not think that a potato is a substitute for vege or fruit. I do not think that it is classified as either. You should be eating a vege or fruit and a good source of protein to balance out the diet.
Apparently a potato + a little bit of dairy = a complete diet regarding protein and vitamins I believe. Thus why the Irish relied on it so heavily as a foodstuff.
I also love mine roasted with canola or olive oil. Aloo gobi is pretty awesome. Mashed with garlic and butter. And then there are these little potatoes in sugar and soy sauce at Korean restaurants (called gamja jorim) that are both salty and sweet at the same time and melt in your mouth