Thanks Matthew. I understand that vestibules require staking. I guess I should have cited rgmaher2259401's review on the Seedhouse page as part of my original question:
"Using the [Seedhouse] rainfly definitely requires staking, so if granite is your thing, you need more tension lengthwise than the poles allow. If you want to stay dry, it has to stay taught, and if anything more than a light rain is expected, you better plan on setting all the guy lines to keep the separation between shell and fly."
A.R.M also refers to the same problem. I was hoping the Helion would be different. Any idea?
I am interested in the Hubba Hubba as well, but I like the two abovementioned tents better due to their extremely small packablity.