The Advantium is amazing. You can choose to use just the microwave if you're just reheating. You can broil using just the top element, or bake using the top and bottom ones. Or speed cook using all three. It pretty much cooks anything a regular oven will--only faster. A REAL (not nuked) baked potato takes about 8 minutes; a hot, bubbly, golden brown casserole takes 12. Cookies are done in 4. And that's with no preheating. It browns and crisps nicely.

Mine's almost 13 years old, so I'm not too familiar with the current formats/installation, but your local appliance store should be able to help you with those questions.

Once you have an Advantium, you will NEVER want to be without one--having 'just' a microwave would be like ditching the fridge for an icebox.

#1: yes. 240V Advantium undercounter = no-no.

#2: dunno

#3: I don't have an Advantium, I have a Miele MW/convect/broil oven precisely because it can be 240V and be undercounter. The issue with this configuration in the Advantium is hot venting air. This is not a problem with the Miele. I have no personal experience with the 120V advantium but have read here and elsewhere it is less good than the 240V for a variety of reasons -- thus I opted to keep the voltage and change brands. YMMV.

But as for #3: Again, I don't have an advantium but many here have stated it does not replace a toaster. Certainly my Miele does not ... though I've never tried at that. My mother just "toasted" a huge batch of english muffins by broiling them in a wall oven and flipping them over and it worked terrifically (to my surprise). So ... I suppose it could be done at that. My Miele has a shockingly fast and hot broiler. But it feels like overkill to use on toast! I have a toaster for that still. I find the speed oven is great as a second oven/MW replacement, but not really so much as a toaster-replacement. Maybe I have insufficient imagination though!

It's been noted here that planning in a shallow drawer to hold speed oven racks right next to the machine is super-helpful. I recommend this move highly!

As for #2, it may depend a little on the brand? I find it hugely helpful in my oven. It's automatic in the Miele so I don't even think about it. It's just basically giving natural convection a little electrical boost: stirring the hot air around. Seems like a wise move to me....

Thank you for the responses!

The undercounter 120V Advantium (the 30"w models only, not the 27") is almost as good for microwaving or convection cooking. The speedcook functions suffer mightily though - it takes twice as long and also relies more heavily on microwaves to cook, so the food won't be quite as crisp as with the 240v. Also, for some reason, only the 240v model has a shelf so you can cook at two levels in some modes.

I have the advantium 240 installed undercounter for over a year now. It may be a no-no but it works fine. No idea why it isn't supported (my dealer said it would be fine).

My concern having it in an island would be the handle projecting outwards. Ours is next to a wall so its fairly guarded but i do notice it when i am working over top of it.

Also while the advantium works great - you will definitely need a toaster. I think you should buy an advantium for speed cooking and ocassional microwave use. Swapping out the pans is a pain and you need a place to store them. Speed cooking is a new way to cook and takes a bit of practice.

i have convection in my single oven but don't use it much probably because we use the advantium for anything time constrained which is usually what you use convection for.
good luck!