What kind of McClaren do you have? I love my Volo! It folds up easily and has a carry strap on the back. I would guess it's between 8 and 10 lbs. It's much sturdier than an average umbrella stroller, has a nice large sunshade, and storage underneath. I highly recommend it!
Ditto that! You can't beat a Mac Volo for ease of use, durability, lightweight and size of kid.
The Combi won't steer for crap w/a bigger kid in it - it's definitely a baby/toddler stroller, IMO. I'm not sure about the other one you mentioned, but I'd test drive it first because some of the light umbrella strollers are so flimsy and they just will be a nightmare to push through the city w/a preschooler.