The muddy legal wake of Prime Trust imploding should worry you if you keep Bitcoin in a self-directed IRA.
Even if you hold the keys in a multisig setup, how sure are you that the protections extended to securities will apply to your stack if the IRA firm goes belly-up? Will you be able to transfer to a new firm without tax penalties if the current one folds?
All that uncertainty paid for with high onboarding and maintenance fees. Hard pass.