I've been happy with the Invo's on the E90. Coming from RFTs before that, they absolutely transformed the car and made it quiet and comfy. They're definitely softer than RFT's when pushed and turn-in was a smidge less confident, but it doesn't really matter on the street. I'm not sure the miles I put on them and I'll have to go check the paperwork, but my rears are pretty much down to the wear bars and it felt quicker than on RFTs.
I don't have direct comparison, but the Z4 came with the Hankooks and I've been very impressed. They are not as compliant as the Invo's, but they handle really well and have great road manners. I'd buy them again.
I'm not sure that helped since my experience with both is on different cars. That said - you're really choosing between two great tires. I'd say Invo's have the comfort bias, and the Hankooks are better handling, but it's close and you won't go wrong with either one.
2006 330i - ZSP/ZPP/ZCW/i-Drive/Steptronic