That's a strange question because Ethernet in one of the basic tools for network in business. As a wired connection it has its own cons of course but it's still the best one and sadly wi-fi can't replace it totally. Yeah, wi-fi is very flexible, it provides conviniency, mobility, general low costs and deployment but for a serious company it's better to use a wired connection. Ethernet is the best one in case of speed including even the LAN connection, it also provides unlimited traffic, totally yours bandwidth and symmetrical speed both for uploads and downloads. RS232 Ethernet provides a much better security too because a physical cable isn't an easy thing for hacking like it rather often happens with wireless connection. And with it you won't face a problem with interferences from other wireless networks too. In case of business wi-fi is only helpful for the work which is strongly connected with such gadgets as smartphones and tablets. It can also be an additional pleasant bonus for your clients/customers.