Hi Pillow,
Just to share...I bought a Combi side by side double stroller when Ryan was born but I decided not to use it anymore coz of safety reasons. Coz the stroller is wide and its just nice to go through my front door. And one day when I was pushing them out of my door, which is quite a challenge because the wheels of the stroller must be aligned straight otherwise it will be stuck and can't go through, then while I was 'navigating', Ryan suddenly sticked his hand out of the stroller and luckily my hubby was alert and told me to stop pushing otherwise I think his arm would have been badly injured. So I decided not to use it anymore just to be safe.
I think a front/back double stroller is safer to use. But the ones I saw at Mothercare and Kiddy Palace were all very bulky and I didn't like the fact that they were still HUGE after collapsing.
Now I just bring one stroller out when we go out. I tell Jade she is not a baby anymore and must walk. I'm using my trusty old peg perego pilko P3 which I bought for Jade, and usually Ryan will sit and Jade will walk. There is a platform behind where Jade can stand. But if she gets tired, I can pull the back down so that the stroller is flat and Jade will sit in front and Ryan will sit behind Jade.