I must admit that this is second hand information (i’ve seen them work at a friend of mine and talked about them), but all that sounds like something is wrong. Yes they do make a bit of sound, but I would not call it very loud. Furthermore they should be very well capable of matching temperature to setpoint.
What mode are you using them in?
Ok, very loud is relative 
But I will not implement them in my sleeping room: I will wake up of this noise.
I use it in normal mode. Set heatpoint manually to 18°C and see what happens in the log.
Room temperatur measured by the thermostat is over 20°C and valve still open. Not good.
That’s weird, I’ve seen it applied and then the actual temperature stayed nicely within ± 0.5 °C of the setpoint.
I just mounted one in my house and it seems to work so far for getting to the right temperature. Still I need to collect some experience. But after a few days I found another issue: I do not get the temperature to my controller or actually extremely rarely. It seemed to work nicely for the first day but then the last temperature event was almost 24 hours ago. But this is something for an extra post I guess.
Have you checked the configuration parameters of the Spirit? (Habmin => Things => Spirit)
The new thread about my problem is here: Spirit z-wave radiator thermostat temperature reporting
I checked the settings and I think they are ok.
I’ve just ordered popp trv, waiting to get delivered and give it a try. Shall be able to comment in a week or so.
I am LC13 user and was missing the feedback capability. Why? In my case it’s more curiosity - knowing how long/when the valve is (or would have been) open. Giving a feeling of how much I’m saving 
EDIT: after more than a week of owning the popp trv - can’t complain. I wish, I’d know of it before ordering my first lc13. Inslucison, set-up was as smooth as with original device. Getting back the temp value as it’s detected by trv.
Must agree - it’s for curiosity mostly. E.g. having the setpoint unchanged and seeing the reported temp going slightly up&down does not tell the story - is it sensor’s accuracy; temp in heating system changes; wind outside or what.
Many thanks @Austris_V ! I ordered them as well to test and I am quite happy for the time being. They are working a lot better than the fibaro thermostat for which I had high expectations and I was disappointed.
Have you played with a bit more ‘advanced’ options ? For example how do you shut them down ? So far I can only set them to the lowest temperature (4 degrees celsius) in order to stop them but this is merely a workaround.
Is there any way I can create a schedule via zwave / openhab ?
I am actually using them in a “pretty dumb” way. Sending 0 (off) or 28 (max) degrees. And creating my own “schedule” from openhab via rules - at preset time, depending on day of the week (work day or holiday) and presence in previous evening - switching ON for few hours in the morning, before everyone waking up or evening - before coming back home.
I don’t believe you can create “device internal” schedules through ZWave/openhab. At least not yet, have not seen any channels for that (but always happy to learn I was wrong and it’s possible :))
After one year and a half one of the two popp’s I had ordered seems to have malfunctioned. It does not report anything to the controller anymore no matter what I do. Tried factory reset, exclude / include, new batteries but no change. i can only use it manually which beats the point of having it.
Check Honeywell Evohome system. You can control everything through wall mounted wifi controller plus you can connect to openhab the whole system and control it through openhab as well. Easier then set up zwave control.