Yes - but a MX5 is going to be fun at any speed ( a demented* one, maybe not-so) - whereas any Boxster doesn't really get into the 'fun zone' until way past practical speed limits (traffic, as much as, legal).
The MX5 joy comes from a light car, that is fun from deliberately-being a hair soft-centred in an accessible way: comfy chassis, free-revving engine paired with splendid, light precise gearchange, in fact nice controls and fine feedback - but not, lots of grip, lots of power, and the tedium that too-often follows.
- oh - and utter-Mazda dependability. Use it just for everything everyday, and it will take it, and take it, and take it, and never hand you a big service bill. And then you still drive it for fun at the weekend.
And the MX5 roof -drop is a thing of joy, stay strapped-in, 1 hand, 10 seconds, done. A simple pleasure. Ditto to reverse when it starts raining.
Shit, now I want an MX5....
[edits for clarity]
* as in enough power, like the Rocketeer etc for 'demented clockwork toy on Lino' abilities. I had a go in c 250hp of turbo'd mk2. Utterly daft. and - Not actually that much fun, the turbo ruined the gestalt.