New member looking for his first Jaguar

[Kasha]

Hi everyone. Thank you for having me. This place is an amazing source of information.
I have posted this question in the Facebook x350 group, but the more opinions I get the better.

I am looking to buy an x350/356 Xj8, the 4.2l in particular. Now, I know that it had undergone minor face-lift before the X358 and with it it received number of updates (sensors, software etc).
What I do not know is whether these updates were significant enough to warrant searching just for the x356 cars made in 2005/06. That is with the updates but before the major face-lift of X358. What are the pros and cons.

I would be very grateful for any input. Thank you.