If I am buying a new mainsail for a boat that originally had a mainsail with no roach, is it a good idea to buy a sail with some roach to try to improve performance?
This could make weatherhelm an issue (let's assume the boat is well balanced to begin with, just a little slow). Would the roach make a noticeable difference in weatherhelm? Would it make a noticeable difference in performance?
Why would a designer design a mainsail with no roach? Isn't it almost free performance?
The people who find fault in what you build typically don't build anything at all.