Hello boys and girls ...
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What would you do and why?
Wow, it's just like being back at school

I can tell you what I would do.
I'd get the 09 and fit the old shock mainly because it's simpler to do but...
You would get the new beefed up frame & linkages with the new geometry. Is it a VIP frame with post as well? That would be a bonus.
If you get the 08 you'll be better off ($$$$$

) and have a pushed shock, but it's more messing round.
You may not mind the trouble though, and as you say, ultimately it's the cheaper option after you've sold a shock.