Nope, I tried lower %'s. Most all TFA flavours I use 10-15% then when the concentrate ages a little up it to 20%. I've seen HuckleBerry recommended 0.5-1% as well, I need 8-10% before it gets good to me. Don't know how people can use 0.5-1% personally I don't taste anything that low.
Honestly, if that's the case you're an extreme outlier and you'll have to work this out for yourself. I'm not trying to be rude or dismissive- it's just that almost no one is going to have experience mixing at those percentages, because they are _very_ high. I have a rather dull sense of taste and smell, but you're using an order of magnitude more flavoring than I would. I don't have the ripe banana you're talking about, but...