[Perfectlap]

The older 911's require way more maintenance than a Boxster which is way more reliable. Those old cars were 'hand made', the Boxster and new Carrera were Japan style assembly line cars. If something goes wrong with either the costs are not cheap but way more costly with the old cars. Also, Boxsters are more "water tight" than old Porsches on build. You're not coming home to another mysterious puddle under your car or something coming loose under the hood.

You have think about it within the Porsche world. The Boxsters/Cayman is the most reliable option from a used stand point. Older Porsches are not meant to be driven high miles in all types of weather unless you can wrench your own cars. The Boxster is as close to a low maintenance as your going to get.

Now the S2000 is a whole other ball game but the'yre generic. If you want more character you're going to have to take on some risk with a Porsche. No way around it. The risk goes up the more you drive it and it sounds like you'll be doing plenty. But a modern Porsche can handle it just be prepared to pay for repairs.
The maintenance aspect isn't so bad, not worlds different than a Honda.
Personally I don't think a Boxster is a good daily driver unless you live in a easy climate with nice roads and little traffic.

unrelated, the S2000s race against the base Boxster in my local autocross clubs. The BoxsterS and the second gen Boxsters are in the class above with the standard 3.6 Carreras. I've matched or beaten many standard Carreras. I'm sure the 3.4 Boxster would have an even easier time of it.