I like the probe tree better than the clip. I wonder if the probe picks up some heat from the grate through the clip. The tree lets me get the probe off the grate and it will hold both the pit probe and food probe. I've never used it with my food probe through.
The only draw back is that it does take up a little bit more grate space than the clip. Sometimes this is important on my 18" but I've always been able to work around it. I think it's worth $18 but can see where some might not think so. Far more people use the clip than the tree. I've only used mine about 12-15 times so I don't know how long it will hold up, but it seems as good today and the day I got it.