When we tried sailing with a tighter rig the boat was noticeably slower in heavy air. When you let the top fall off in these conditions it depowers the main, and opens the slot. The final step before sailing is to set the mast rake. Pull a tape measure to the top of the mast on your main halyard and measure down to the center of the hole on the backstay chain plate. This measurement is easy since it actually works for either style deck.
Rake is hard to set from boat to boat because there are so many variables.
The exact location of the mast fore and aft may differ slightly, the location of the main halyard sheave, and the size of the halyard shackle and thimble can all be different. Even if they are not, the correct rake for one mainsail may not be right for a mainsail made by somebody else. The rake you carry is determined by the amount of weather helm you want, and is controlled solely by the length of the headstay. Sails with different amounts of camber, and different leech profiles, will produce different amounts of weather helm. So use this measurement as a starting place, and then go sailing.