Ok - so I have a Sinner Mango Sport (Red Edition) velomobile. I have owned this for 18 months (ie 2 summers) and have now done 9500kms of mostly commuting in Brisbane. My velomobile is my daily, all weather commuter. I commuted via road bike for 3 years before that. So I feel qualified to respond
Firstly, justification. I think we all go through this. I know for me it was a lot of money. We're a 1 income family so there were times I felt guilty spending $12k on a bike, when my roadie was still in good nick. All feelings of guilt disappeared the day it arrived. If it was stolen or destroyed tomorrow, I would definitely spend the insurance payout on another one. No doubt at all.
Re humidity, I've never lived in Sydney but I can't imagine its hotter or more humid than Brisbane
The mornings here are 95% humidity even in winter. So long as you pick a velomobile with sufficient ventilation you'll be fine. I normally ride without my hood, except when its very cold or raining. I just like the open feeling of head out riding. This also means I don't heat up when I stop. If you're working reasonably hard, you simply couldn't stop in a fully enclosed velomobile for more than 30 secs without steaming it up. The Trisled Avatar is impractical for this reason, where as the Trisled Rotovelo, mango, quest etc have sufficient ventilation even when stopped.
Everyone thinks the velomobile must be hot. But even here in Brisbane, on my 18.5km / 40 minute commute, I don't even bother carrying water anymore, since I was not needing it. The protection from the sun helps a lot I think.
The advantage of a velomobile comes in when you can build and maintain momentum, since the aero benefits increase with speed. In stop / start riding the weight is a penalty. It all depends on your route too. Climbing hills are slower, but then the speed is too great downhill and you may have to ride the brakes to stay under speed limits etc. If you ride mainly bikepaths, other bikes will hold you up on downhills too so you may not be able to use your speed advantage.
2 thirds of my commute is hilly and quite stop-start / speed limited. The last third is open and flat, but often there is too much traffic to just roll through at 50km/hr. So even on an 18.5km commute, I am only maybe 5 minutes faster than I was on my road bike. On a flat open road, I could maintain 45km/hr. But who commutes via a flat open road ? The more I see of the bikepaths in Perth, the more I think a velomobile would be ideal there. Particularly punching into headwinds.
I've never ridden an open trike with a FF fairing so can't comment with any authority about their aerodynamic capabilities. They don't appear to provide the other advantages of a shell though, like full weather protection (wind, sun and rain), luggage space, road visibility, enclosed drivetrain etc. Even without my hood, my velomobile keeps my shoes and shorts nice and dry in the rain. Only my chest,shoulders and head get wet. Even my backpack and laptop remain dry stowed away behind the seat.
I hope this helps. There is a rotovelo in Sydney if you want to try to meet up. I think I really made my mind up the day Nitramluap (Australia's first mango owner) rode my commute with me and I found I couldn't keep up with him. It also helped me believe it could handle my hills (up to 18%) and the gutters / ramps etc I have to contend with. It also settled all my safety concerns, which I laugh at now since I feel the velomobile is considerably safer and more visible than other bike on the road.
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