Good Day Nick,
I wanted to pass along my experience with my 33OI #207. I added a second headsail (as opposed to a cutter rigged inner staysail).
I got the idea from the Discovery 55 (Cruising World 2005 BOTY), according to CW, the staysail was an either/or proposition with the jib.
In my case, I configured my second foresail with a club foot in a simi-self-tending configuration (per Brain Toss's Rigger's Apprentice p. 255)
This has several advantages in addition to what Brain discusses in his most excellent book.
1. This gives you a staysail large enough to do you some good in moderate conditions.
2. By using a hanked on sail, a storm staysail can be used as needed.
3. With the club foot, the stay sail can be moved out to one side and the jib can be poled out to the other side, for downwind work.
4. With this configuration the sail can be sheeted on the C/L for windward work.
5. You will not need running back stays.
I am half way through a Caribbean loop and am very happy with my boat and the rig. Although I seem to be able to go about 10 deg. more to wind than with the jib, the great advantage is having a moderately sized sail that can be easy controlled in blustery conditions. There a some pics on my site(geocities.com/water_magic)and I will be adding a section on my rigging modifications later. If you need anything else sooner there is an email link on the site.