I have used a similar sealing iron (I built my first packraft with one – you can see it in my older videos) and it works fine for sealing, but the ironing surface is too wide for most purposes so it is a bit slow because you have to use the tip or the edge of the iron instead of the flat surface.
The heating tools that I have used do not have accurate temperature gauges, so I can’t say what the actual sealing temperature is, but I will buy a laser heat sensor tomorrow so I can check the ideal sealing temperature and I will report back after that (tomorrow the price drops from $100 to $20 at my local hardware store!).