Haven’t heard much about the Zebralights lately (also haven’t paid that much attention either).
Regarding your question to HCRI emitter (diode) options. Top suggestions here will be Luminous SST-20 3000/3500/4000k, Quad Nichia E21A (see Virence.com), or Samsung LH351(B or D), along with Nichia 219.
If you haven’t read this short thread yet and are considering the Convoy you should . Takes a 21mm driver and is very accessible to mod.