So much depends on variables - your lifestyle, your children's development and likes/dislikes. Ours are 2.7 years apart, and whilst within normal limits both are long, well built and frankly heavy. The elder goes to a child minder two days a week and is used to being pushed miles back and forth on the school run. He will walk, but is so slow, and then will suddenly tire and want to ride. We have a lot of slings (I like the Connecta too) but it was a matter of weeks before the baby was too heavy to carry. He is on the 110 centile so very long - my friend's baby is a tiny, elegant little girl, so our needs were both so different. I first tried a tandem - the Britax b dual which I already had (the older version) with a tandem seat, but toddler( if I can call a 3 year old that!) refused to get in it with the carrycot on. Frankly I don't blame him, there was hardly any space for him, and no view. It was a pain to push up kerbs too, even with just the toddler in the main seat, and his feet were in the shopping basket if he was in the rumble seat. We then got a Mountain Buggy Plus 1 which was great, as the baby lay in the back, and toddler up front as usual. However once the baby outgrew his space at the rear, it, ( which he did very quickly) it wasn't so practical. In any case toddler was so jealous of the baby that we were having to make adjustments so he didn't feel displaced. So having tried - and disliked immensely- the tandem set up, we looked at side by side so both had equal space. We wanted the MB duet, but couldn't afford it even second hand, so in the end went for an almost new, v4 (separate hoods) Out and About Nipper. It's light, a dream to push, and both children love it. However the triangular footrest meant toddler had one leg hanging to the side, and it's shopping basket is non existent. When we realised Out n About had a new one out, the Little Nipper, we went for it. Tyres that don't puncture, squarer front, 4 wheels, basket, a really easy fold, and so light - it's great. It's been - and still is - fantastic. It goes up to 5 years weightwise. Even when toddler wants to walk - and he's 3.5 now - his seat nicely takes a shopping bag and holds a ton of stuff. I was so glad of it the other day when he had a meltdown in a store, ( over a chocolate bar) as I'd somewhere to strap him in and corral him. Don't know what I'd have done otherwise. It's narrow enough to go through doors too, ( haven't got stuck yet) and I now realise that the duet would have been too tight for them given their sizes .For me it's a no brainer. I plan to keep it for another year at least given it's so great for days out - well for any trip really. The Uppababy is great - and if you get it for child 1 makes sense - but otherwise I'd go for the Little Nipper. But it really is horses for courses, and only you can make that decision. It really is what suits you