I am using one currently and if you have the ethernet module, you can see everything on the webpage as well.
When you do automation rules, just send the mode before you change the temperature (set it to HEAT, then set the temperature). I had some inconsitencies until someone here recommended trying that, which seemed to do the trick.
Also, clear the programming if you are controlling it from the M1, if you change the time for each of the cycles to around noon or midnight (i forget which, it is in the manual) the time will 'clear' or dissappear. That means the programming is cleared for that particular cycle. Do this for all and you will have no conflicts (this was recommended).
brings up a topic - why spend on a sophisticated programmable thermostat (TR40 like) when all the programming will be done by ELK or software? All we really need is the RS232 / RS485 communcation in a stripped down thermostat. No logic needed in the thermo.
But you also want something that works with the Elk. From what I understand, the HAI model is the 'cheap' one of the M1 supported stats. At around $140 (if I remember the prices) it is much cheaper than the TR40 (closer to $300 I believe). Granted you can't put messages up on the screen....
If you have the heating/cooling being controlled by the Elk, then it really is an easy to use thermostat for any manual changes. Just go over to the unit and hit the up or down buttong. That is it.
Can you do the same integration with less cost? I'm not aware of an Elk compatible thermostat that is cheaper than the HAI (except maybe an X10 one? That would most likely add reliability issues though).