We haven't used ours for a while, it worked ok when he was less than a year, but last time we used it in the Lakes he was 1year10months and I biked up to Whinlatter with him on the back, it was a workout but doable, the worse thing was the way the front wheel started to lift on the steep sections, quite disconcerting to have no steering. Mind you Mini-Obi is a bit of a mutant, he's not even 3 yet and about 15.5kg and over 1m tall. One of the disadvantages of our seat is that it doesn't recline, so if he fell asleep he tended to loll forward which didn't look that comfortable, although it didn't seem to wake him up. The next model up reclines although this wouldn't suit you as this lessens the room in front of the kids legs even more. I guess Dad kicking child on every pedal rev wouldn't help with sending them off!
With our number 2 due in December, next summer we're going to experiment with something like
this one. Even if it's crap it won't break the bank. A few blankets and teddies and I recon it will be zone to hang out in. Also doubles as a cheap double buggy with big wheels for festivals etc. We're not keen on the ones where one sits behind the other.