Jennifer, it is very dangerous to ask a group of Hilleberg fans to extol the virtues of their tents. You may have just opened Pandora's Box. ;-)
Since I'm about to sound like a Hilleberg add, I need to disclose that I have never gotten a penny from the company, or compensated in any way...and with the amount of advertising I've done for them they owe me at least a Nammatj 3GT or an Unna...(are you reading this Petra?) hahahahaha.
OK, so down to your question; A Hilleberg might not be for everyone. They are simply too heavy for many people to even consider. When I go on solo summer backpacking trips I've been using my BA Copper Spur. It is a great tent for that purpose, and the lightest I'm willing to go. I'm the kind of hiker who likes to have a real tent when I get to where I'm going, and I don't care for trekking poles at all. That said, if I'd looked into the Unna or the Akto before I bought the Copper Spur, I likely would have gone the Hilleberg route for even solo camping.
Now on to their bigger tents; Ventilation is excellent. I can see why in some of their smaller tents with one door, a mesh inner tent would be nice in hot weather. But in my opinion any of their tents with 2 doors (Staika, Tarra, Saivo, Kaitum, Keron, Saitaris to name some) have excellent ventilation to the point of the standard yellow inner being fine year round. The Saivo in specific with it's vents at either end and two huge roof vents is a venting machine.
I use my Hillebergs year round, even for good weather, summer camping. The same thing that makes them excellent for going to the north or south pole, makes them great for me as well...longevity and ergonomics. These tents last forever (almost). There is a couple named Simon and Lisa Thomas who have ridden their motorcycles around the world for the past 10 years, from both the most northerly and southerly roads capable of being motorcycled in the world. They have used two Keron 4GT's for the past 10 years (replaced their first one after 5 years). In my opinion, 5 years of living out of the same tent from the hottest deserts of the world to the coldest arctic areas and having it last that long is a testiment to durability. When you get a Hilleberg catalogue they include swatches of tent material...standard ripstop nylon, and their Kerlon 1200 and 1800 fabrics. The swatches have a tear started in them already, and the idea is to rip the material apart to see the strength. The Hilleberg fabrics are pretty much impossible to rip by hand, especially the 1800.
For ergonomics the ease of set-up by one person, in foul weather, is incredible. So is their space. When Hilleberg calls it a 2 person tent, they really mean it's a 2 person tent, plus gear.
So in closing, Hilleberg will always be my tent of choice from here on out, simply because I like having confidence in my gear. Unless weight is your absolutely highest priority (and for many it is), I can't see a reason NOT to go with a Hilleberg. Even cost will be lower in the long run, with how long they last.
Even though I'm thrilled to death with the new Saitaris, the Tarra is still the most impressive tent in their line-up to me. It has the space of a tunnel, with the bombproof and easy set-up of a dome. For motorcycle camping for 1 or 2 people the Tarra probably couldn't be beat by any tent on the market.