Hi
I have the icandy peach which I LOVE as a single. Brilliant steering, plenty of space for stuff, comfortable for child; really great if you are going to be doing a lot of walking. As a single, even though it is a fairly heavy/sturdy thing, once put together, because of the steering (which is WAY superior to any other buggy I have tried), it feels incredibly light. A friend who has converted to double has also been pleased.
I bought also with the intention of converting once number 2 came along. However, with my second due in 2 weeks time the plan has changed. Number one is almost 2 and a half, and instead we have got a buggy board, and will probably on occasion use the buggy for the babby with toddler standing, and sometimes have baby in sling, generally depending on level of fowl toddler mood...
The other thing I was going to say is I don't know if you already have any kids, but by the time my son got to 2, he uses the buggy for far less as he wants to walk everywhere, and also, the seat on the peach isnt huge.
BTW I got mine on ebay which took the total cost down to about £500 excluding car seat; I definitely think its worth the list price when you see how much others cost, as I do think it's in a league of it's own quality wise, but its definitely worth a look on ebay.