Hi there,
We've got a four-wheel pram with a reversible seat and so far I love it. It's a Love N Care Adiva Sport. We don't have probs with the wheels because the big wheels are always at the back, if you know what I mean - so turning circles are always tight etc. My DS is 9kg at the moment, and the seat part must be approx 2kg. I don't have any probs picking the seat up and turning it around with him in it at the moment, although if I'm honest it will be harder/impossible to do this as he gets bigger. Just means thinking ahead before I put him in it though! Also, we can't fit a toddler seat to ours.
We did tons of research before buying a pram, and found one that suited us and our needs, so I can only advise you to shop around and ask lots of questions, which you're obviously doing. Good luck.
Andie