I have to agree with Markus here. Rpis are cheap considering what you spend on the other hardware (power plugs, dimmers and whatnot). Get both of them. Rpi4 will most likely work, considering how big the rpi community is, however will take some time before the software is adapted to the rpi4.
Regards S
Iāve started this topic a long time ago and really good to see all the discussions.
Man do I love the OpenHAB project!
Anyway, shortly after opening the topic Iāve made the decision to go for a Intel NUC. And until today Iāve never regretted this decision. Iāve been running the OS (Debian) and Openhab without ANY issue (except for my own screw ups in the config ofcourse)
But I had a now a mix between āolderā OS, and OpenHAB v1 and v2ā¦so started last week to build my system again from scratch on the NUC.
Now on the latest Debian 64-bit build and the latest OpenHAB v2 stable release.
Had some issues with drivers because of the 64 bit OS, but all is up and running. Now slowly building up the smart home again 
But I can really suggest to step to a NUC in case you are experiencing issues on the Pi and/or want to have a more reliable and āprofessionalā base unit. The NUC is SUPER!
Shortly after running on PI, Iāve switched to pre-NUC small box size pc with 16gb ram and 250gb m2 hdd not sure about cpu 4cores some intel
running elementary os and kodi as main hts unit, OH running as docker image which I canāt recommend more, itās simply perfect.
All crucial OH data are being stored outside docker container, easily to maintain, work with and backup.
RPiās are great, using couple of them, but for OH Iād recommend something bigger as well as @JdeJong
I run OH2 in ODroid C2 units these days and Iām very happy with them.
Iāve helped a few people remotely who have Raspberry Pi units, they always seem slow to respond by comparison.
yeah odroids are great, personally using them to decode h.265 tv standard (EU)
I was very happy when I started with my rasp3. Itās perfect for openhab and it has a power consumption near the zero 
However after a year of use I can see its limitation (the same you can read everywhere): first big issue I had it was the breaking of mmc, after I bought a good quality mmc and all itās ok.
Second limitation is the small quantity of ram, from OH2.5 Iām near the full and Iād like to install a DB instance, graphana and a small instance of nextcloud. Now I donāt know if is better an upgrade with a rasp4 or better a nuc. Now the CPU is ever near the 2%, so I donāt think a nuc will give me a performance increase and the power consumption of the nuc is not trascurable
The 4gb pi4 is a considerable step up in RAM, if thats the limitation. The CPU improvements might not make material difference.
Once you have bought the pi, a case with heatsink (or fan), a new PSU you still wont be approaching the cost of a new NUC or the fanless ?BRIX equivalent. The cheap atom fanless PCs can be ok, but the price will be higher and only the most expensive of them have more than 4gb RAM.
I suppose the alternative is if you have any other NAS or 24/7 machine running. For example, I use a fraction of my Plex server.
Intel NUC can be considered if you would like to use it for more fuctions. I have I7 with 8Gb ram + SSD. It runs Plex server + OH. OH 2,5 eats roughly 800k ram but database handling is switched off currently. I use Graphana + Influx.
My Plex is remote and I prefere to have OH in house. So I think rb4 should be ok for all I need to have in house. Otherwise an amd64 architecture it will be more flexible for the future.
Old thread, but I recently flashed Mr Chromeboxās updated UEFI bios and have had good success across kernel updates. Seems the problems with kernel location have been sorted. CN60 looks to be a viable solution for x86_64 openhab.
On 32 bits from my experience 2GB RAM is enough. Running with 28% of RAM used (but without grafana and persistence at the moment). The board is OrangePi Plus2e. The only problem i have: the system freezes hard sometimes, requiring a reboot. I was never able to retrieve logs even via SysRq, however it looks like a kernel panic.
Bought a 4GB Pi4 for that reason, will build an mk2 controller with hard drive
BTW, does anyone know of any HW diagnosis software for ARM? I would like to test the board and locate the issue after decomissioning
Kernel version?
root@orangepiplus2e:~# uname -a
Linux orangepiplus2e 4.19.38-sunxi #5.85 SMP Wed May 8 14:20:48 CEST 2019 armv7l GNU/Linux
Is it known problem ?
Also this can be confused with another phenomena: OrangePI is veeeery fastidious about power supply. Despite the core is running at 3.3V input power drop below approx. 4.8V sends the board to reboot. If your connections are flaky (for instance you decided to power the board via GPIO connector and use jumper wires with discrete 1-pin connectors like these: https://www.amazon.com/dp/B07GD2BWPY), this can happen sporadically. Furthermore, during bootup consumption increases, sending the board to endless loop of reboots.
But i solved this by feeding the power via jack, using thicker wires, and using screw terminals for power distribution. Now power voltage measures at steady +5.3V on boardās test pads near the GPIO connector. The board crashes much less often but still does.
No.
But if powering is not good, this is more then expected. Good PSU is the 1st thing you have to fix in case of troubles. Thatās common for all boards. Some hangs, some crashes, some clocks down, some silently clocks down ā¦ I hope you power the board via proper power connector now?
This particular board - Orange plus 2E - is the best H3 board you can find on the market. It must run stable.
Moving to most recent kernel 5.4.y is highly recommended. I am running few boards, also Openhab on H5 based board and didnāt have not a single crash in months.
Yes, as i have told just above.
To tell the truth i like eMMC, and i feel sorry about replacing the Orange. It quite fits the purpose.
I was playing with Dell Edge Gateway 3000 (it is much more expensive than RPi) and some of Aaeon Boxer devices. Both come with eMMc and RS232/485 options.
If you havenāt made your mind and have budget for experiments try above.
Me too 
Are you possibly running openhabian or did you use the āregularā installation process?
There are also lower performing NUCs, which are not overpowered like the i7 verion (if you run a dedicated OH server only)
Intel NUC BOXNUC7CJYH2 Celeron J4005