Hi Schaf...
I have started my project off in the past year, and did start off with OpenHAB1. While I liked it, and have to admit it was very stable, I like you decided not to invest too much time into it now because OH2 beta was actively being tested and fixed. I stuck with it during the beta and had very little problems. IF I were starting now, I wouldn't even consider 1x because of the time to transfer it over...unless a certain binding you want didnt work with 2.0 yet, which I doubt since you didnt mention anything but MQTT and this project...
To reassure you, from what I did as far as a migration is move my config files (being only the sitemap, items, rules, and a couple HTTP scripts to control my thermostat and homemade sprinkler system. For me it started right up, but here is what you need to know that is important if you started andthing with 1x and go to 2:
1 - Don't just copy all the config and "plop" it in the new directory structure...place them individually (items, rules, scripts)
2 - Spend some time on the old "all in one' config file and split it properly to the new format. You'll notice it's properly split by binding now and SOOOOOO much better.
3 - Don't worry too much about the automatic detection nor let it scare you...manually moving the items, rules, and scripts and properly setting up the config is all that is needed.
4 - And for me this was a pain and the biggest point - don't waste tome on 1.x pretty icons if you know you are going to move to 2.x! They are moving toward SVG's from PNG's and if you use the "CLASSIC" interface with the new setup, all will still work, however make sure you config the classic UI to use the PNG's from the PaperUI (PaperUI is the "setup/configuration" interface). You'll find the new place for icons is under conf/icons/html and both types go there regardless. One more point: I could be wrong, but as I remember in the early beta's of OH2, IF you went with the new UI over the "classic", you had to use SVG's. Now I think you can select which type, but I already started with new ones so...maybe this whole topic is mute.
5 - And this was important for me: If you want to turn on and off an item/switch from and HTML POST, you have to call it like this:
10.1.1.15:8080/classicui/CMD?IsDusk=OFFNote that was different from
10.1.1.15:8080/rest/items/IsDusk/state=OFF (I think, don't remember)
Important if you get Alexa (Echo) for your birthday! I wrote my sprinkler system completely in python, PHP, and MYSQL, running on a PI and I communicate with OpenHAB this way as well.
6 - You in fact really now have 2 projects to choose from in this forum. You will find Computourist did a great job porting this all over to run on ESP8266! It works great, and the MQTT topic structure is the same. You can use SONOFF and many other devices that are ESP8266 with his code. Unless you really need distance, I would use this completely. ESP's are cheaper than an Arduino+Radio, and you may find easier to start off with. You dont however have as many IO's, but there are so many ways around that, and you can still have it talk to an Arduino if needed. The Gateway/Radio setup can be finicky for a beginner.
THEREFORE, having said the above, there is not too much Computourist nor PAPA will teach you or document that you cant apply to 2.x, just be careful where you put it is the big thing. You can mess with the autodetect and "things" or whatever they are called now. (You can tell I don't use then nor could care less!) But one day I will and I do see many of interest! So as far as the knowledge on this forum, it's still very good and all applicable for 2.x as far as I'm concerned...but I repeat myself: Be careful about mainly the config files because they are split now!
I think there are so many good reasons now to move on from 1.x...I love the new HABPANEL, something that never worked with 1.x correctly for me if you want to use a cheap tablet for an interface. Speaking of interfaces, the new ones to me appear so much more clean and modern.
One more point though - IF you are uncormfortable finding your way around and think you need alot of hand holding, maybe 1.x might be better for you because PAPA spends more time to document and help people than anyone else. I think most of Computourists examples are 1.x too, not sure, so if you want to apply directly and just "copy/paste" (which I discourage), I would in fact stick with 1.x Most of my stuff, what little I have, is 2.x. I'm slow and not as good with electronics as everyone else, so my progress is hindered greatly with circuits even so I have all the programming skills.
Hope it helps!
Jim