one pan of cookies, banana bread (one breadpan), a cake pan with some fish in it for two people, couple of potatoes, oven fried potatoes for 2 or 3 people, a few rolls, one 8" cakepan with a favorite chocolate cake recipe, any time I want to cook something small and it seems silly to use the big oven. Haven't tried doing bread only because I normally do 2 loaves at a time. I wasn't sure how much I'd like it but somebody suggested that it makes a great second oven and she was right. Wish I could find a 11" or 12" diameter non-stick cookie sheet to use in it because the metal tray on which I can put food directly has a groove about 1" in from the edge.

It is overkill but your manual should tell you which heating elements are on in each different mode - true convection (probably convect cookies in your range) has all the heat coming from the rear element around the fan - so there's no bottom or top heat. The other modes probably have some combination of top, rear, and bottom heat. Except for things that require bottom heat like souffles and popovers and that shouldn't use convection at all, most things can probably be cooked on just true convection unless the rear element isn't powerful enough. You need to read your manual and experiment a little.

Actually, I think the cavity is the same size. There's no difference between the 30" new one and the 24" one except trim, and the optional water tank instead of plumbing. I doubt the 27" has a different sized cavity from current by more than a centimeter or two, and is probably exactly the same. The opening of mine is just about 18" deep, 12" (usable) across, and 8" (usable) high. I can fit my graniteware roaster, barely, or my large (17") Pyrex baking dish. I don't know what the side racks are like on your model. Mine are C shaped pieces of stainless which are attached to the oven walls and the location of most of the hard to clean crevices. The others are around the drain, which is in the center bottom. Again, I don't know if yours is the same, but I doubt it's too different. You can make anything for a small, nuclear family in this oven that you can cook on convection. That's hot air only--no other heat source. Most things you bake should do fine. Maybe not a souffle, but even then you can cheat and use baking powder and salt to give it rigidity. The convection in the small oven seems a lot gentler than the big fan convection in the big oven--I assume because it doesn't have to be stronger for a small space. I'd be less worried about delicate baked goods here. Plus, add 30% steam and the weight of the air might (speculation here) counteract some of the ill effects of the blowing. A butterflied (spatchcocked) chicken will fit in one of the pans. A vertical chicken will not fit, and you wouldn't want to clean up even if it did because of the spatter. Similarly, you could fit a small turkey (I've never cooked one under 22 lbs. so most of them seem small to me...), but, again, because of the spatter, I'd use a roaster or one of those covered clay turkey pots that are supposed to be so good (they don't come in 25 lb. size!). I often cook for mobs. One can't invite A without B, C, D, E, F, and all of G's kids. The combi-steam is my smallest oven. Probably a similar size to some people's counter top "toaster" ovens (way bigger than real toasters). I usually have the main in the big oven (Gagg 30" single), the made ahead sides in the Advantium on convection, and the alternative main in the combi-. People rave about using the combi- for breads, and, as I said, I intend to try it, but my standard batch of challah is three loaves and they just barely fit in my mother's 27" Gagg single. They're a little more comfortable in mine. They don't like convection at all, but even if they did, I could only fit one in the combi- at a time, which means a smaller batch (hard to accomplish) or retarding the rise. This is also a recipe which can flow over if the yeast is too active, and a potential for getting into those danged crevices. The cavity size is that kind of European oven that is lovingly (not) known as Easy Bake. You really can cook anything that you can feed to the number of people who fit in a tiny European apartment in it. Like four or five. And you can bake in small quantities. Not necessarily room mother amounts of cookies, but you can even do that if you have patience and time. If you're not bothered by the crevices you can cook just about everything that fits, though there's no broiler. Oh, and you can't reach in and turn things or stir them or, probably, baste. Opening up isn't good because you let the steam out, but there's no room inside for hands, so you'd have to take things out to tend to them. I generally only use mine for stuff that can stay in without attention. In a suburban home, you really should have (or have room for an easy retrofit) a larger oven. For a tight little bijou flat with two chairs and a sofa, it's plenty.

Your oven does not have a convection cooking mode in it. GE didn't add a convention cooking element to the 240v Advantium (letting you select temperature as with a conventional oven) until the mid-'00s, which yours predates. The Advantium 120 has always had a convection oven; now they all do, but the early 240v ovens had only the halogen lights and microwaves for cooking. (the newer-design A240 wall oven also has a larger interior with a wire shelf, a interior light that stays on during microwaving, and is several inches shorter, with a custom-sized drawer that fits underneath the oven cutout opening to hold extra trays for upgraders).