Kit. I cannot answer your question, but can draw an analogy perhaps. The wired USB-Ethernet adaptors are pretty robust - I don't trust wifi for anything that requires a persistent, low latency connection (my use-case: gaming) - so my laptops that don't have wired ethernet do use these adapters and they are solid. There's stories of old of USB->Parallel printer adapters not working on parallel port BoBs - that I can understand - you can't sustain the timing characteristics over a USB interface and Mach3 would be hitting the p-port directly and wouldn't go through the HDD software layers required to allow the USB interface to operate. Also, the purpose of the AXBB is for UCCNC to offload higher level machine motion instruction into the AXBB for local pulse-generation - the critical timing aspect is localised to the AXBB, and from memory UCCNC rolls a 100ms or so buffer of data to the AXBB (and that might be adjustable). I'd be reasonably confident in the reliable use of a USB/Ethernet interface.

OIn the other hand - I wouldn't trust any WiFi link in an electrically noisy environment and with the prospect of the missus donning the rubber gloves (shudder) and using the microwave oven.