Kevin, the Stix are intended to be placed 4-5" into hard ground (not the soft ash pile of an existing fire pit). This will be solid enough for 2-4 cups of water in your pot. With the Stix being 9" long, that leaves you 4-5" between the ground and the grill to make your twig fire. If you are thinking of building a fairly big "warmth fire," then you'll need to rethink the way you employ a grill and support Stix. My technique is to have the grill be placed in a small alcove off to the side of a roaring fire, and shove hot coals under the grill as needed. A few people have told me that their full size grill sagged horribly under heavy load when placed over the hottest part of a campfire. I've never had this happen, but it's likely that serious heat (and weight load) can reversably alter the physical characteristics of such thin titanium rod., allowing it to sag. After it cools down, you can easily bend it back the way it was, and no harm is done to the metal (it won't break).
By the way, I should disclose that I am in collaboration with Rob Kelly of QiWiz. I have made the cross pieces for his FireFly stoves, and as such, I needed to acquire both sizes of his stoves, to make sure the pieces fit (and also the mini grill I make for the smaller stove). I also had trouble being patient with the smaller stove while waiting for a boil (my technique was probably lousy), but the larger stove was no problem for me at all. One proper load and I was set with boiling water in 7 minutes. Rob says that he can do the same thing with the smaller FireFly, so I'm sure that technique, and experience, is the key.
Edit--spelling, and added something about grill sag