I did a few straightening sessions this evening with the heat gun (on pretty low heat setting). It's not perfect yet but it's definately improved... it's at least 50% better looks like. That's already going to improve flight a lot.

I stopped for now because I was noticing a side effect from not doing it perfectly... some covering between two ribs was getting a little looser. It's all good enough to fly though right now I'd say, so I'll quit while I'm ahead for now and make it perfect later after giving it some thought.

Maybe I'll try a go with the iron as well.

Thanks for the help