Would you be willing to pay for additional contend?

[usr]

In the shape of well-rounded addon packs, sure!

In the shape of the "insert coin to fly plane" scheme of RoF, or even those "pay to pwn"-field mods - not in a hundred years. It made the full release version of RoF feel like a demo, a demo i had to pay real money for. The RoF model might be acceptable for people who are fully obsessed about the sim, but it really excels at making the occasional simmer feel closed out. Looking back, i feel more satisfied with paying for "The Beta" than with paying for "The Demo".

A little "app store"-like feature where reviewed and quality-controlled campaigns and missions could be obtained... why not? Just make sure that it's very accessible to content authors and does not make free content impossible (the famous mobile phone app-stores don't do that either).