Those top tube mounting seats are a pain. They damage your paint job, need you to pedal with your knees wide to get round your kid and are a pain to fit securely, slipping frequently.
Additionally, if you are out riding on your own and get in a traffic accident the footrests you attach to the downtube have some nasty bolts sticking out. I had one stick in my leg once and leave a nasty wound after a pedestrian walked out on me (I shouted and he spun round going even further into the road staring stupidly at me, sigh.) Tried to stand up and fell because my leg didn’t work after hitting the footfest. Ended up screaming at the ambulance staff that I was going to cycle to the bloody hospital as soon as my leg started working again as they refused to take my bike with them (leave it unlocked at the scene of the accident? They’re ‘avin a larf!)
So, that’s a downvote from me for those seats 🙂