Sean, I have used the shades from Catalina Direct (CD).   CD was very responsive in after sale service on some issues I had installing the blinds.  It’s a little tricky to put in the snaps correctly-I destroyed a few of the snaps and asked CD to send me replacements, which they promptly did at now charge.   I have learned there are suttle differences in snaps and the male & females must be identical.  I found it helpful to snap the sets together before installing them to make sure the pair was compatible.   I found it a challenging install-do ALL the small windows first to build up your skill set before tackling the bigger windows.  Because the big windows are wider towards the aft than the bow side of the windows, and the big shades are rectangular cut (not angle cut) the narrow end needs to be tweaked - I will be attempting to sew a few of the pleats at the front (bow side) of the window to deal with the extra fabric.  
Again, very pleased with service by CD, but a little tricky to install.  Buy a set of quality snap pliers to help in the install.  Fabric and hobby stores sell the snap pliers - maybe CD does too (ask them).  Best of luck.

Wally, 
Yes, the excess pleats in time sag, the bigger the window, the worse the sagging.  The fact that the bigger windows are not perfect rectangles creates a challenge.  To deal with the excess pleats, I plan on bringing color match thread and try sewing together the ends of a few of the sagging pleat end.  No doubt, screwing in the pleat at the top of the window is a challenge.
On my previous boat (Catalina 30) we tried plastic sliding shades “Peak a Boo shutters” and had issues with the shutters not sticking to the window.