Helion's and TAE's reactors have some things in common but they are quite different. Both merge two FRC plasmoids into a single FRC in a central chamber.
The differences are:
1. Helion accelerates their plasmoids to higher speeds.
2. TAE keeps their merged plasmoids in a semi- stable steady state after merging. Helion compresses them when they merge in the central chamber with a very strong magnetic pulse.
3. TAE keeps replenishing their merged FRC with neutral beam injection. Helion lets them dissipate after the extreme compression (pulsed).
As far as I am aware, both have roughly have the same energy confinement time but have different plasma lifetimes, pressures and temperatures.
There are benefits and disadvantages to both. One could imagine TAEs design as a pot without a lid that is slowly boiling on the stove.
TAE has to constantly add heat to keep it boiling and eventually replenish the water.
Helion's pot is more like a pressure cooker that boils really quickly (until it blows steam). Then they put a new pot with cold water on the stove and start over again.
I am not aware of Helion observing higher plasma stability at higher temperatures. The thing is that Helion does not really need long plasma lifetimes, due to the pulsed nature of their reactor design. Helion's challenge is to have strong enough magnetic fields to quickly compress and heat the plasma. TAE's challenge is to keep their plasma alive and hot for long enough.
So far it looks to me like Helion's reactor core will be MUCH smaller than TAE's. The former will be around the length of an oversized shipping container, including direct conversion technology. TAE's PB11 machine is going to be 80 meters in length. So Helion can build their reactors off site and ship them in one piece, maybe even with enclosure, shielding, etc. TAE will have to assemble their reactor core on site and they will need some fairly large buildings too. That drives up overnight costs. I mean look at size of that thing on page 65 here:
https://www.nrc.gov/docs/ML2109/ML21090A288.pdf
Helion also has a more efficient (~95%) energy recovery and conversion scheme due to the pulsed nature of their reactor. They can vary energy output and load follow by varying pulse frequency. They should even be able to replace gas peaker plants, which would allow them to charge a lot more for the same amount of power produced (up to 200 USD/MWh).
To the best of my understanding, TAE can not do any of that. Their direct conversion (if they manage to develop it), will be interesting and they currently estimate it to be only about 30% efficient. That also means that they have more waste heat to deal which requires more cooling equipment. Helion's reactor core essentially produces the same amount of waste heat as a diesel train engine. So it is quite simple to cool that on a small footprint.
On the other hand TAE's reactor is going to produce about 350 MWe/core while Helion's will only produce 50MWe. So multiple Helion cores would be needed to produce the same amount of energy. The waste heat can also be used for things like industrial and residential heating, so it is not completely wasted.
As for neutrons:
Helion's reactor only releases 5% of it's energy as neutrons. That is quasi- aneutronic. And mind you, those neutrons can be used to do some work as well (breed Tritium for more He3 and make a few extra MeV at the breeding blanket).
Also note that while PB11 is much more aneutronic than D-D-He3, they still produce some via some side reactions. Plus they have a lot of X- Rays to deal with due to the much higher temperatures involved with PB11.
Personally, I think that the market is big enough for multiple reactor designs and we will see several of the fusion companies succeed in different niches of the market. There are a lot of different fission reactor designs out there. So why would fusion be any different?