Help me choose a Boxster - which would you choose?

[Perfectlap]

at this weight imho a roadster greatly benefits from at least 240 HP. Less and you have to do a lot more of the work. More than about 300 HP and the car gets a little to easy to drive.
The extra power makes the platform come alive off braking and out of slow turns. There's an extra kick there that changes the experience. In real world settings the extra power is very very nice when highway merging or passing someone who is hogging up the fast lane. Standard commutter sedans have a lot more power these days. An accord V6 has as much power as a late 90's BMW M3.

As for the cars your considering. Keep looking. Ideally you want a car that is NOT close to home. One that is kept in year round warm weather. And one that is driven frequently but not far.
A cold weather car with mileage over 70-80K better have some major maintenace work done already like shocks, clutch/ims/rms. Otherwise you'll be paying for that and those repairs can easily run $5K. Winter-driven cars just take a much harder beating thus require much more work by the original owner if they are considered to be a good deal. Case in point I often hear of Southern California cars with mileage over 100K that barely need any work.