I've used the ThermoPro Twin TempSpike unit a few times. I love it. I suspect that it'll replace my FireBoard unit.
I had a confusing few hours setting it up because I don't like the way the Owner's Manual is written. I'm sure it makes sense to someone who already understands the product, but I had zero entry level knowledge and I almost always interpret things differently than what the author was trying to explain.
As one of many examples, the owner's manual reads, "When both probes are placed in the Booster for charging, the Booster will be automatically turned off." So I thought that the unit turns off when charging. When I couldn't find the instructions for shutting it off for storage, I texted ThermoPro Customer Service for help. The response was that it'll turn off after five minutes when the two probes are in their storage positions. It doesn't have to be charging.
So from my perspective, the instruction should read, "When both probes are placed in the Booster
as if for charging, the Booster will be automatically turned off." But those of you who don't have Asperger syndrome may not be troubled by these instructions that I view as incomplete.
There are several reviews on Youtube.
I recently discovered
this unit from Combustion Inc. I'll probably buy one. It may reduce my wondering if I have the IT probe at the proper depth.