Think tank Retrospective 20 or 30

[RÅW]

Hi Guys,
I found a Think Tank Retrospective 30 for $120 is it worth it? I plan on carrying my Nikon D7000, 10-24, 24-70, 70-200 and camera cleaning accessories. Would this bag be to big? Is it worth getting even if I have the Think Tank Streetwalker Harddrive?
For the people that have the Retrospective 30 can you carry a tripod in the bag?
For the people that carry a shoulder bag, when you walk around the city is your camera and bag strapped to you shoulder? Or do you put your camera back in the bag after shooting and pull it back out when you want to shoot something?