Something that is not considered in certification of single pilot jet operations is the matter of currency. The jet sales people tend to gloss over this vital aspect of owner-driver flying.
A commercial pilot flying a complex aircraft on an almost daily basis is less likely to get into trouble than a PPL with not much prior IFR time doing the same thing maybe once a month.
As someone observed, a new Mustang is way more user friendly than an old Baron, but if you fly any fairly fast aircraft 50 hours a year and that's the sum total of your flying, unless you have plenty of prior relevant experience, you are likely to struggle. Three approaches in 90 days barely covers it if that's all you do.
And put all your faith in the automatics at your peril. Modern automatics rarely fail, but when they do they always choose the worst possible moment.