The PO 8900 movement is not better than the SMP 8800 movement. In my opinion anyway and I've owned both.
The 8900 has a slightly longer power reserve--5 hours more. But in real life this difference is unnoticeable. The 8900 has a jumping hour hand that allows you to move the hour hand without hacking the seconds and minute hand. This sounds like a cool feature but in real life it's not. You will rarely use it unless you travel across time zones frequently. And the downside is that you lose a quick set date feature that is present on the 8800. The 8900 can be a real hassle to change the date. Plus, it's a thicker movement. You could offer me the exact same watch except one with the 8900 and one with the 8800 and I would choose the 8800 every time.