Mine are the older Colt Ace conversion kits. The floating chamber is great as it helps simulate recoil - a feature missing in the blowback style conversions. One major foible: once the floating chamber gets leaded up, it's as if it was welded to the barrel and it takes quite a bit of effort to free it.
Mind you, the newer Colt Ace kits are straight blowback and like the Ciener have a aluminum slide.