The first player has definitely a huge advantage. The advantage is bigger than it's in regular connect four as far as I know. 

Hmm, I don't think Pop-Out is a solved game in the way you can tell exactly where to move and not, but I can't tell for sure. 

Hi,

Pop out gives a much bigger advantage for red, but similarly in my opinion when blue has got a break due to red's mistake it makes breaking a lot easier as well.

As far of my knowledge nobody has brute solved connect four pop out style, mainly because there is no real logic behind it or rules to be enforced..

At moment I am experimenting different pop out styles to try further my understanding on the topic as well,

Regards,

Warren