I cannot say about the quality of kit compared with Model slipway, as I haven’t seen a caldercraft kit in years, and have NEVER actually had a Model slipway in my possession to compare.
If you look for comparrisons between kit you will come unstuck.the best way is to treat each kit on it’s own merits and to build that kit to the best you can, overcome any problems with it, and just enjoy the build.warts and all.
neil.