> Are curved spiders really much better than the typical 4 vane
> straight spider? I am considering one for a 12.5" f6 Newtonian
> telescope.
What do you mean by "really much better" ?
As far as I am concerned they are inferior in ANY aspect, except maybe for astrophotography when you're bothered by diffraction spikes.
If your "really much better" is performance-wise, just look at any high peformance reflective planetary telescope around (including Pic du Midi, and Donald Parker's own 16 inch) : they ALL have plain ol' "typical 4 vane straight spider", and for a good reason.
Bratislav