The serious painters in my previous club (I've had to move due to job relocation) used Sikkens primer as a replacement for K&B, and said it worked well. I don't have a personal experience with it though. If you're looking for something quick and pretty easy, I've had excellent results with Coverite 21st Century primer from a spray can. It's about $4.00 a can. Fills pretty well, dries quickly, and sands to powder with little or no sandpaper filling. I use it exclusively for small paint jobs, like cowls, wheel pants, misc. parts, etc. I've had zero compatability issues with KlassKote and also PPG Concept Urethane. I know most serious painters don't seriously consider anything from a rattle can, but this stuff is actually pretty good.