Some interesting battles there.
I've my flux at home, but have just setup a dumb turbo with a Tacx blue matic for weekends. I set it at level 3 resistance, which was what zwift told me to do, but it felt like very hard work. I'm sure I was working harder with a higher heartrate than I normally would for the same wattage. I'm also doing it with a bike with 16 gears, and smaller front rings than I'm used to - so when trying to raise my effort for a sprint I was spinning out.
I've never been on the Alpe, as I've just unlocked level 12 - but might try the tour tomorrow, what could possibly go wrong?