No experience with either Lezyne or Silca pumps. I've been using two versions of Topeak Race Rocket for years that have a similar screw on hose as the Lezyne pumps.
In the case of Topeaks, the hose is permanently attached to the pump and can handle both presta and schrader valves. Not as pretty as the Lezyne or the Silca...
I have unscrewed valve cores a couple of times. If the valve cores are tight, then it shouldn't be a problem. Also, I've heard of people lightly greasing the threads of the valves to avoid the pump head sticking to the valve core.
To be honest, I don't use the mini pumps that often. I guess I don't puncture that much, maybe 2-3 times per year.