In 2019 I purchased a Tarptent Stratospire Li directly from Tarptent in America for £658.16 and after it arrived in the UK I had to pay another: Import duty £56.69, VAT £104.80 and Parcel Force handling fee £12
I justify the cost by the number of nights (69) I've wild camped last year and will hopefully again in 2020.
My tent has a solid interior and Dyneema floor. The dyneema feels like a thin plastic bag but has been surprisingly tough. As yet the inner tent floor has no holes in it and I'm loving how waterproof it is, the water just beads up and runs off it or I shake them off when I take the tent down and it's basically dry. The Stratospire goes up tight and stays tight all night, so I've not had a problem with the dyneema rattling in the wind and it was windy when I used it over new year. The Notch Li is a similar design and I would happily buy one, but my only worry is the solid inner on the Notch looks like it hasn't got a solid roof like the Stratospire inner, so in usual UK weather, condensation may drip through the roof mesh when it's windy. But I'm only guessing. I would buy from Tarptent again, the tent is well made and their service was good.
Considerations not mentioned yet are, because the dyneema is so light weight the tents can be bigger without a weight penalty. My 2 person Stratospire Li weighs 807g and I love having 2 porches and all the space inside but it's sometimes harder to find a wild camping spot due to the size. Not a problem with my trusty Nordisk Telemark 1 which weighs about the same.
Dyneema also needs packing more carefully, not just stuffed in it's bag, it's recommended folding and rolling it up or it will damage. It has been suggested the dyneema will wear out faster than silnylon but mine seems fine so far. Also the Stratospire and Notch are held up buy walking poles which is fine until you break one during the day while walking with it, but having said that, it's great being able to adjust the height of the tent to suit the weather conditions (how much draft you want through it). I'm now planning my gear list for the Scottish National Trail and which tent to take, and it's a real hard decision between the two, they're both good tents for different reasons.