Lot of comments on AP being mandatory. I did my IFR training in my 6, which is certainly more sensitive than a 9. We would often go 2 hours of flying / training and i was not allowed to ever engage the ap, including the briefing and approach setup (quite a challenge in the 6 - look away for 5 seconds and you have blown heading and altitude targets). Also, every 6 months i go shoot approaches. While i do one full approach on AP, the other five and all of the flying in between them is hand flown. Solid 2 hours of hand flying. Yes, it is mentally taxing to fly these birds in imc conditions, but consider it far from unsafe to fly these birds without an ap. That assumes, of course, you keep up your hand flying skills.
Would i fly four hours in cruise in imc without an ap; Not likely. Would i land immediately as in some danger; absolutely not. It is all about your skills and how you have honed them. If you do ALL of your approaches on an ap and have lost the skill to hand fly an approach in turbulence, then yes an ap is mandatory. Problem is, what if it dies in flight? Probably better to just keep skills sharp.