I am fairly new to the Caldera system, but have been testing two of them on recent trips. One is the Keg, the other a Snow Peak solo mug (28 oz).
For a perspective, here are both with several water containers as a comparison:

With the Snow Peak mug, I just use one of the caddies. Caddiess weigh about 1.5 oz each (top or bottom).
Some pictures the Snow Peak set up using one caddy:

Because of how the Snow Peak sits on the cone, you can see that the cone is almost twice as tall as the mug. So I use one caddy to protect it. Plus see note later in this post regarding use of caddy and mug.
You can pack the keg without the caddy, but really need a stuff sack to keep all the components in one package. This set up is good if you want to use the keg as a multi-use item, for boiling water and as a bowl.
Although the keg and the SP mug have the same capacity, the mug is wider and shorter. This makes it a lot easier to eat out of the mug. The Keg has a band at the top to help pick it up without being burned. I still have to use a glove. The handles on the mug make it easy. So for ease of use, the mug wins hands down. For packing and weight, the keg wins if you don't use the caddy at all.
Lids – I have replaced my Snow Peak lid with foil, and will do so with the Keg.
For breakfast and dinner, I usually drink coffee or some other hot beverage. Breakfast is always instant oatmeal, which requires some sort of mug bowl. Dinner is usually something in a bag, so a bowl/mug is not required to eat. For breakfast my 40+ year routine is to start with a cup of coffee. While drinking the coffee, I prepare the oat meal and eat it while enjoying my coffee. This requires a mug and a bowl, which is why the Snow Peak and caddy works well. But… the groves in the caddy collect particles that are hard to clean easily. In the desert I am not washing pots very often, because water is scarce. So I drink coffee in the mug, eat my oat meal in the caddy, then boil more water for a 2nd cup of coffee and drink the 2nd cup of coffee in the caddy, while scraping the sides to clean it. Or I may just drink some water and clean the caddy at the same time. When done, I wipe-clean both with a bandana.
My next few trips will be the Keg, without the caddy, and an attempt to use the keg as a single pot/mug. We shall see if habits can be changed :)
The Keg or SP fits perfectly in a side pocket of my GG Murmur, with a 1L platty in the other. On my Conduit, the Cones and 1L platty will not stay in the side pockets because of the angle of the pockets. They move foward while moving and eventually fall out. So with the Conduit, I use 2 1L sport bottles in the side pockets and the Cone goes into the pack. Actually with either pack, there is always ample room for either cone.
Regarding storing the cone flat in a pad or other location. These newer cones have a slot construction to assemble it. Each end is joined by sliding them together. The least little bend and it becomes very difficult to slide the two ends together. So I would hesitate to pack it flat… however, I will be trying this method on one of my trips soon. Plus, placing stove components is separate areas is not the most efficient, especially since the pad is one of the last things I pack. Plus in cold weather, you might want to stop for some soup at lunch, and you have to take several steps to get all your stove components.
I have never tipped over any stove or pot, but take care when cooking, plus I take the time to select a flat surface to cook. With the Caldera, this is not an issue. In the desert, wind is a concern when cooking. The Caldera shines at this. With my Snow Peak giga stove, I ended up buying their 2 oz windscreen, because wind was such an issue.
So overall, the Caldera is definitely a winner. For me the jury is still out for the mug versus keg, due to convenience. But in the long run, weight will probably win as it is much easier to pack the cone into the Keg. If I can learn to eat drink with just one piece of equipment, it is an extremely versatile and lightweight cook system. The Keg, Cone, Stove, Spork, Foil lid and empty fuel bottle have a total weight of 4.0 oz.