Aluminum and steel are night and day when you cut, drill, or mill them. As neophyte mentioned, galling is a much bigger problem with aluminum, so titanium coatings (there a few different kinds these days, but other than TiN they're prohibitively expensive) are good to have. Steel isn't nearly so bad on that front, though, and TiN has other disadvantages - teeth can't be resharpened, since that will grind off the coating, and while the titanium adds heat resistance if you go past that point it quickly gets trashed. Heat is also an issue: aluminum stays much cooler than steel when cut, both because it's softer and because it's a great heat conductor. A lot of the heat from cutting aluminum will be drawn out into the surrounding material quickly, which is less true of steel. Tooth offset also makes a difference, although I don't off the top of my head remember what the proper offset is for steel and aluminum. Offset is how each tooth is bent to the side, and is sometimes alternating (left, right, left, right) or in various patterns (left, left, right, right, or left, center, right, center, or others). My guess would be that if you used an aluminum blade on steel you'll burn it up very quickly and that if you used a steel blade on aluminum it'll gum up. You're all materials blade is probably just a reasonable compromise between the ideal blade for each material, but buying the specific blade for each metal will give you the longest life and cleanest cuts.
Have you looked into getting the blades resharpened? Carbide blades can usually be resharpened a few times so long as you haven't lost any teeth. I would spend the money to have a shop do the sharpening; cutting steel the angle at which the teeth hit your material is very critical, and having it wrong can send a carbide tooth flying. It also needs to be done differently from having a wood cutting blade sharpened, so make sure they've worked with metal cutting blades in the past. My local saw blade supply generally has a quick turnaround for the service. A good saw blade seller will also have lots of good advice on how to get the most use out of your blade and keep them sharp longer.
