[as far as dropping z-wave, I don't think it was the change in the frequency, as they also decided not to put z-wave on the 1000 or 1100. what the reason was, only logitech knows. it's actually something I don't know...I just kind of accepted it for what it was
A couple of potential reasons are first, Z-Wave is an entirely closed system controlled by a single vendor, Zensys. They control everything from the silicon on up. Ecnet, on the other hand, is a proprietary Freescale Semiconductor protocol based on the 802.15.4 mesh networking standard. They probably licensed it for considerably less than the cost of Z-Wave.
Second, it's interesting that they chose a little known protocol compatible with nothing ( afik ) .. however, Freescale is one of the major Zigbee Alliance members, Zigbee is also based on 802.15.4, and the upcoming RF4CE protocol is now a Zigbee standard. The RF4CE protocol, which was based on Freescale's BeeStack, has a lot of consumer AV manufacturers behind it. Zigbee, in general, is used by many of the high / mid end controller manufacturers like Crestron and Control4. Zigbee is also competing with Z-Wave on lighting and other enviornmental control ( Zigbee has the lead in commercial applications, where Z-Wave is ahead in the consumer space ).
While Zigbee is a propriety protocol, it's controlled by an alliance of companies rather than a single source. It's also based on a standard hardware / radio / networking platform that is multi-source and license free.
Since the basic radio and networking protocol ( 802.15.4 ) is the same for Ecnet, Zigbee, and RF4CE, it would be possible to make the H900 compatible with RF4CE with only a software change ( provided they have enough hardware resources to support the Zigbee/RF4CE stack )
All this together makes me think that this was a very forward thinking change for Logitech. If RF4CE does get some traction with the major AV manafacturers that are part of the RF4CE group, including Samsung, Sony, Philips, Pioneer, Panasonic, NEC, Mitsubishi, and Motorola, this would potentially give the H900 hardware the ability to directly communicate with, including feedback, consumer A/V gear via RF.
Personally, I think this would be the holy grail. All just speculation on my part of course.