According to Hennessy's website, their Hex tarp is 144" x 120". The Typhoon lists as 120" x 90", and I'm kind of assuming that's out to the "point" on the sides. That would make the Typhoon 2 feet smaller and 2 1/2 feet less wide at least. Seems like a pretty considerable loss of coverage, kind of as you've described above.
I have the HH Hex tarp...and frankly, it's darned forgiving. It's plenty 'tall' enough that there's a lot of safe room underneath it. I could potentially sleep low enough to bring the edges of it to the ground if I needed to.
I'm debating on either sending it in to 2QZQ and having them attach doors to it or buying the Typhoon from HH. On one hand...a second tarp that comes with doors. But...if the tarp is considerably smaller than the hex, I may well not be happy with that. The other option is still only having one tarp...but having doors on the ends that give me a considerable amount of dry workspace underneath that tarp when the wind is howling, the rain is flying, and the beer is flowing.
So...that's the decision I'm trying to make. Weight for me isn't a major factor in this particular choice. Any input towards that effort would be greatly appreciated.