What are your opinions on this?
Theoretically, chain bar gives a wider range of motion but the 4 bar maintains a more level, vertical plane of movement when moving meaning less drivetrain readjustments when you need precision
A chainbar provides a greater margin of error for stacking, a 4 bar would be less sloppy and more reliable, but needs to be made with more precision. Although they do need to be a little more precisely built than a chainbar, they don’t have as many parts that could come loose and cause the lift to malfunction. In my opinion, a 4 bar would be better.
Our team has had success with a chain bar on top of our DR4B. It increases the number of cones we can stack by about 5, since it lifts them about an extra 13 in.
I’ve been working on a 4-bar. But (with my style robot, at least) it doesn’t work very well. I plan on switching to the chainbar. In all honesty, both are good, but if you can, I’d do 4-bar.
Our robot uses a 4-bar and it has worked very well for us. We focus a lot on the loader, and I think it would be much more difficult to move your claw to the position you need with a chain bar. Also (correct me if I’m wrong), but I don’t think a chain bar would be able to support a heavier roller intake, which seems to be the most reliable way to get cones off the loader. You can definitely make either work though.
I think 4-bars are better, but chain bars can definitely support heavy rollers. Because Ri3D used a chainbar for their mogo intake, and I sure hope no rollers weigh more than a mogo
Our bot uses a chain bar for the extra height. Four-bars are a little more complicated/precise to build, but not by much and they are more reliable in general. I personally feel that you can get the same performance out of a chainbar that you would of a four-bar if its built right.
I would use a chain bar, lots of teams if seen reveals on and a team in our area uses a chain bar to achieve internal stacking.
Didn’t think of that, rollers should definitely be lighter than the mobile goal 
I think that is largely depends on the design, it you need less then 180 degrees of motion the a 4 bar is the way to go because it is lighter, takes less space, and you can rubber band them way easier, for more then 180 degrees of motion i would do chain bar over offset 4 bars.