I’m considering getting either of these two energy monitors. Can anyone describe pros and cons of the two different systems (other than number of channels)?
I took a brief look at the other product you listed and I can not say much about it, but it does look more expensive.
When talking about the IoTaWatt as a customer I can say the pros are:
- Easiest plug and play energy monitoring solution out there compared to others (sense, etc.)
- Best support from the creator (@overeasy) who continues to improve and listen to the community
- A simple but functional user interface to customize the things you would like
- 14 inputs are more than enough. I used to want it all, but have trimmed things over time (not needed)
- Great integration with third-parties (EmonCMS, PVOutput, and many more) for retention and graphing
- Built in graphs and retention if you do not want more advanced reporting; still good out of the box
- It just works yet continuous development and future plans provided in blog posts
I sure others here can provide you with many other pros of this solution. These are the ones I can think of off the top of my head.
Asking in this forum you are likely to get a slightly biased response 
I’m delighted with my iotawatt which was easy to setup and works flawlessly.
Support is excellent.
There are some useful math functions (e.g. max 0, min 0) That make it possible to use 1 CT to measure the flow in both directions on a phase which is useful with a solar PV system.
More maths and CTs allows adding up each of the three phases (I’m on a 3 phase supply) to enable Calculation of total consumption, generation, import and export.
It integrates well with Emoncms and other capture/recording systems but has useful graphs built in so for simple reporting other systems aren’t required.
There are some limitations due to the underlying device Https connections to external reporting servers isn’t possible and there are some restrictions if you want to hide the device on a secure vlan (but hitting that sort of problem assumes you have enterprise level networking and switching running on your network.)
In summary, Value for money = satisfaction - price. The iotawatt is excellent value for money.
I don’t have a GEM, but considered getting one for years. I do have an ECM-1240, which is the precursor to the GEM. When I got it, about a decade ago, it was the best value. I learned a lot about my consumption from it. The ecm-1240 has two main channels and 5 aux channels. This was impressive a decade ago, but is not enough to get a really good picture. The ecm-1240 does not have any local storage or viewing of data. I had to keep a PC on 24/7 to get data from it. I was using Smart Energy Groups to view the data. It worked well. But then SEG started charging and the process/price was greater than I was willing to pay. I then found emoncms, which was free at the time. Some time later I found IoTaWatt. I wasn’t sure 14 channels would be enough, but decided to try it out. I now have two IoTaWatt devices and am happy with them. I see much more active development here than at Brultech, so I expect this will only get better over time.