I've been looking at basically the same tents for the same intent and purpose: Alpine/Mountaineering, ~<5lbs, 2 person, ideally a vestibule, ~40" tall, long enough for 5'10" plus winter bag, reasonable footprint.
I'd love to hear your feedback on the Vaude, as its come down to the Rab Summit Mountain Bivi + tarp or porch, Nallo 2, and now the Vaude Power Odyssee (its been off of my radar).
FWIW, I've been leaning towards the RAB due to simplicity, eVent, and storm-worthiness, but hemming and hawing nonetheless due to lack of included vestibule. Which has led me to the Nallo 2 and now the Vaude Power...
Edit: Vaude is saying the Power Odyssee (external poles) is 2850g/6.28lbs vs 1870g/4.12lbs for the Odyssee (internal poles) - which if that's the case the Power is too heavy. Do you have the Power or the reg Odyssee?