Hi
I have owned both and there are pros and cons to both but I do prefer the vibe because of the following;
Brake on the handlebar - single most useful change imo as I really struggled with the footbrake on the sport which i often had to bend down and do by hand. this was no good when ds1 was walking as he had a tendency to run off and if I needed to run after him it took me ages to get the brake on by which time he had a good head start on me.
Hood is much bigger, hood on the sport was useless as a sun shade whereas on the vibe it is the most versatile sun hood i have ever seen.
Folds with the double seat on - although this takes a little while to perfect I can now do it quickly without having to lay the buggy on the floor, doubles seat on the sport was sometimes tricky to remove.
Cons of the vibe are that the back wheels feel slightly wider and the access to the shopping tray (which is actually bigger than the sport) is difficult as it doesnt have a flap on the side that you can let down like the sport.
I would definitly go for the vibe despite draw backs.
Hope this helps
A-M