You are likely to get the good old "use the search function" really quickly, but from all I had gathered when I did all of my research, there seems to be a consensus that either works very well.
There are a few die hard Calvert guys that will tell you they hold the record, but the fact is Assassins are not on nearly as many vehicles. Bottom line, the Assassin has a lot more tuning available, but from what I have heard, once they are set, you are pretty much good to go like a Calvert.
I ended up going Assassin, and while I have not got to the track yet, (hoping to this weekend) I can tell you that I am more than satisfied so far. Even on the street, the defference between what I had and what I now have is night and day. I never suffered from traction loss, but a very poor ride and extreme rear separation on launch. Now when I get on the car, you can tell the rear is staying put and the car has much better grab even on the street.
Bottom line, take your pick. Either way you should be happy.
As stated above either one will work and do what you want it to do... IMO the Assassin bars are a better design because the "force" is put on the spring eye and not the spring itself like with the Caltrac. This equates to no bent springs which tends to happen with high HP cars using Caltracs over time... Also the craftsmanship on the Assassins are much nicer as they are all tig welded.
With that said, no matter which route you go, shocks are more important to getting everything to work...
Thanks for the clarification. I never knew the benefits of either. It seems the assassin has more benefits and I'm sure will be setting records as more get out there. I personally bought assassins just for the fact I bought my complete front end with everything, rear springs, gas pedal and his traction bars. Buying everything from him gave me dealer status so I saved some cash on the whole package. I'm a long ways away from getting to use them.
I will say smith is a great company to do business with. He answered various questions I had for a few phone conversations before I ever placed a order with them. The stuff showed up on time and the quality is very good. The whole kit came with every but, bolt, washers etc that were all grade 8 and lock nuts. You can tell they spent some time making there front end kits. It was like $100 to have them bend and mount my hard brake lines. They looked perfect following all the bends in the front end.