Slightly OT:
With all the mud slung at SCT's for their central obstructions, this is
certainly a point in their favor when it comes to wide aperture scopes.
You get the aperture without an impractically long tube, and you can
use a focal reducer to get low power. With Dobs, wide aperture means
long tubes or fast optics.

-Larry Curcio.

Of course while my Newtonian is F4.06, the primary mirror in an SCT is normally
about F2, so you are in reality not getting away from fast optics, what you
have avoided is the need to parabolize the mirror but the optics themselves are
faster.

The central obstruction issue is still there, the Newtonian being 25%, the SCT
being 35%.

And at F10, with a focal reducer you will bring that scope down to F6.3 which
means you will not have as wide a field of view as is possible with an F4
scope.

jon isaacs