After sailing a J/24 with a relatively deeper keel per boat length and a fin keel at that, you should expect better windward performance with that keel configuration in comparison to the shoal bulb keel on your 41 DS. You are somewhat spoiled because of that, I fear because the Hunter keel is not the best for keen windward performance. i have a lot of experience with Selden in mast furling spars and you can achieve good windward performance (for a cruising boat) with a nice flat (and perhaps newer sail). Again, you cannot expect the same windward achievement with an in mast furling system, but when I have used them on various boats, I have been pleased with the performance. Regarding the location of your genoa lead, the way I figure it out for most conditions is to position the block so that when you gradually turn the boat towards the wind so that the luff starts to curl, the entire luff should curl at the same time. If the top half of the leading edge of the sail starts to curl before the bottom half, your lead is too far forward. If the bottom luffs first and the top luffs last, then the lead is too far aft. Put it in the perfect spot, then the leading edge of the sail will luff at the same time and that will offer you the best windward performance - at least from that standpoint. The one time you might want to bring the lead aft is in the very heavy stuff as that will make the upper half luff, which will depower the rig spilling air aloft, which will help you sail flatter before shortening the sail (or furling it in). Luff tension is another factor that affects windward performance in various wind velocity conditions. In light air, you want to ease things off and as the wind pipes up, you can add luff tension. If you get a curl in the luff, that is too much tension under any condition. As you add luff tension (in the genoa or main) you bring the draft forward. Ease it and the draft goes back. Tension the outhaul on the main and the draft comes down and ease it and the draft goes up. With an eased luff, the draft goes aft and you flatten the leading edge of the sail more which will help in windward performance with a finer entry as apposed to powering up the sail by bringing the draft forward. But, when the wind pipes up,you need more luff tension. Vang tension in the light stuff should be off more as should the backstay adjuster, if you have one. The traveler should be pulled to weather and as the wind pipes up, the traveler can be eased to leeward. When it comes to sail tension or tension anywhere, the old saying, "when in doubt, let it out", has a lot of merit. Sometimes it just doesn't seem like the boat is moving freely along and if you start loosening stuff up, she begins to accelerate. The bottom line is, while you are sailing along, it's fun to try different things to see the cause and effect of the changes.