I went with a single wall over and the Advantium, both of them purchased and installed separately for the reason you stated above. Here's mine:

Unless you're *really* tall, I think you'll regret installing an Advantium above double ovens. Unlike a MW, the Advantium has a drop down door and, when used as an oven, the door gets hot. If you mount it too high, you risk burning your arms as you pull something out of the oven.

I did mock ups to figure out what height was most comfortable for me. I think the bottom of my unit is 46" or thereabouts above the floor. I'm just under 5' 4".

HTH!

An alternative is a Combi/Steam oven like Miele, Wolf or Sharp make.

Sorry let me clarify, looked my op and it’s a little confusing.
I don’t mean installing the ovens. Is there an advantage to purchasing each unit individually instead of the combination item that GE has that is a double oven wall unit? The only advantage I can think of for 2 individual units is if one breaks it is easier to repair.

Another advantage is that you can mix and match. Maybe that doesn't feel important right now, but in the future, you might find that you absolutely need another feature (combination steam would be the most obvious candidate). If that requires replacing a single appliance, it might be in budget. If it requires replacing two appliances, most people wouldn't do so.

And in fact, you could even do that right now. You don't really have to buy both appliances from the same manufacturer. If -- just to pick a random example -- you prefer the GE Advantium and the Miele CSO, there is not reason why you couldn't do that. Visual experience won't quite match; but I bet you really don't care after a few months. Functionality trumps most of this.