The problem is, low neutron fusion reaction cycles require a very high pressure/temperature/plasma density to reach peak reactivity, substantially higher than D

The problem is, low neutron fusion reaction cycles require a very high pressure/temperature/plasma density to reach peak reactivity, substantially higher than D+T and D+D fusion. If we do eventually progress to aneutronic fusion test reactors, we will first have to get neutron-emitting fusion reactions working to the level of substantial net power generation, even if a given test reactor only lasts a few months before neutron irradiation becomes unmanageable.