Here I am content with the HAI OPII board (#1 and #2) and its current connections to the serial & IP touchscreens, UPB, X10 (now XTB), Omnitstat2, Z-Wave, Russound all functioning with very quick responses and never skipping a beat. I never pay attention to it; as it just works.
I have one of two HS2 boxes in which is built on a Foxconn Atom D525 modded a bit with a PicoPSU (with a battery charging circuit) and two slot hot swap drive cage which I utilize. The other is using a BCM "commercial" style motherboard. I do have issues with the "simple" one with few hardware connections and with the "not so simple" one with the multiple IO devices on it.
IE: a hardware disconnect of the z-troller will make the software/Z-troller disfunctional until the PC is rebooted. I have though now turned this into a bit of a phone managment box using the W2C device and removed those functions from the primary HS box as it was sometimes tripping up and causing some WAF grief. (something as simple as the thermostat turning itself on to 90 F at whatever randoms times can cause some WAF stuff too.)
On the second box I have some 18 serial connections plus XX HSTouch connections. Old HS2 just looses memory until it doesn't run any events and if I leave it be it will reboot itself (BSOD). I do have it controlling the touchscreens (standby, wol, screen off, screen savers et al).
New HS3 is still a bit buggy(I purchased it) (and evolving) and will it will some time yet for a production version that you can utilize everyday box; unless you want to be a "test" participant or just wait a couple of years(?). The architecture of the software is totally different and will allow the "plugins" to run autonmously somewhat from the core HS. That said I am doing that today with one plugin that was rewritten to run independantly of HS on my little Linux Seagate Dockstar; now maybe two years 24/7. Today this application is linked to the HS page and can be controlled by HS but is not at this time and runs just fine by itself.
I currently (and its a WAF) prefer that the HAI panel control (automate) its connectivity autonomously and quickly and with no glitches at this time; but that is me and my personal opinion. The house is relatively soundproof with solid core doors. I do hear some loud dialog between the wife and the parrot (they do not like each other) and then some software HA glitch which triggers some odd TTS debaucle or this or that.