Hey Paul, I don't have the Lenslight Mini, but after looking at it on the website, here's what jumps out at me:
1. ZL SC52: $64.
Lenslight Mini: $160.
2. ZL SC52: 10 light levels + 2 strobe functions.
Lenslight Mini: 2 light levels.
3. ZL SC52: Low or high level available with one click from off.
Lenslight Mini: You can order either High first or Low first as an option.
4. ZL SC52: Can use commonly available AA alkaline or NiMh batteries, OR a 14500 lithium-ion cell for increased output on high.
Lenslight Mini: Uses CR123 or RCR123 battery.
5. ZL SC52: Uses electronic side switch.
Lenslight Mini: Uses forward McClicky mechanical tail switch, allowing momentary of constant on.
6. ZL SC52: Uses XM-L L2 LED, in either cool white or warm white, for a more floody beam.
Lenslight Mini: Uses a Premiun Bin HiCRI XPG-2 LED, probably giving a narrower beam.
7. ZL SC52: Glass front cover with Gorilla Glass AR coating.
Lenslight Mini: Patented Aspherical focusing system.
8. ZL SC52: Stainless Steel pocket clip attached with screws for bezel down carry.
Lenslight Mini: Removeable, reversible Delrin pocket clip.
9. Both lights seem well made and water resistant.
Main differences I see are the ZL having 10 light levels and electronic side switch, and running on common AA batteries (with lithium-ion option), while the Lenslight Mini has the Aspherical focusing system, uses CR123 or RCR123 batteries, and uses the mechanical rear tail switch.
Both seem like fine lights (I have the SC52w, so I am biased), but they seem like somewhat different creatures. It might be more apples to apples to compare the SC52 to something like a Led Lenser AA light.
Anyway, those are my thoughts.