For the past several years I have been running surveys on user preferences for wireless field sensor networks.
Here are the latest numbers. This survey was for tank level measurement devices. The question was, "Which wireless standard are you using or will you be using?"
WirelessHART (IEC62591) 49.44%
proprietary standards 19.10%
IEEE 802.11 16.85%
It seems that the marketplace is speaking very loudly. Next week, the ISA-100.12 Standards Convergence committee meets in Orlando during ARC Forum. Based on these results, they have a very important job to get done.