Thanks for all the replies. This helps a great deal.
The smokes are wired into the panel (as are keypads) so I'm optimistic on their re-use.
One poster suggested the EOLs belong in the field rather than at the panel. Curious as to why you feel that way. Having them at the panel makes install and maintenance so much easier. Does it really make that much of a difference?
Homeseer is where I will start looking for software.
Now to scrape together some funds for the Elk and Z-Wave devices.
Anyone have experience dealing with either zwaveproducts.com or orchestratedhome.com??
Please check the smoke detectors carefully. There are several 2 wire smoke detectors that are compatible with the ELK on Zone 16 (only). Make sure if you have 2 wire smoke detectors that they are compatible with the ELK (see the installation manual for the Elk-M1).
If you have 4 wire smoke detectors then they will be compatible and can be used on any zone. For 4 wire smoke detectors you will have an end of line relay to supervise the power (or you should). I am guessing you have 2 wire smokes though.
If the smokes are 10 years or older you might want to consider replacing them.