The mainsheet? When not racing, if you have two people, can't one adjust the main on the coachtop? Can you turn on the autopilot for a sec? Won't the boat balance out so you can leave the helm? A traveler in the cockpit is necessary for racing, but makes it a pain to walk around the cockpit, makes a good, folding cockpit table difficult, and the mainsheet swinging through the cockpit in a gybe can be dangerous. When cruising, we use the cockpit table daily, often while underway for lunch. Yeah, an aft traveler is nice for tweaking sails, but there are reasons most cruising boats don't have it there. decide what your primary use will be, if racing, go the J.
When sailing shorthanded, a good autopilot is more important than traveler position.
In the survey, pay a lot of attention to potential wet deck core on the J boat. I'm not accusing, just saying......
I can't believe anyone would waste the space in a 40' boat to put in 2 heads, but that's just me, opinions differ. To me, 40' is a small boat, one head is plenty. If you have another couple aboard, you should know them well.
Both these boats will handle well, and I wouldn't be concerned about docking either, but the J will steer like a race car. No question it will drive very precisely.
The Sabre will have more water tankage. 30-40% more, which is significant in determining cruising range and comfort. This may eventually encourage you to make longer voyages, but so may the additional speed of the J.
Go look at both boats, take your wife. Sit in the cockpit, move from the wheel to the companionway. Lay back on a cockpit seat to read a book. Which boat is more comfortable? Take your time, crawl around in all of the unfinished spaces, look at the seacocks. Which boat has soft wood plugs tied to each seacock? Find a place where you can inspect the hull to deck joint. Unfinished spaces tell a lot about a boat and it's maintenance.
Check the passive ventilation. All other things being equal, I prefer boats with big Dorade vents.
Look in the bilge. Check the extra equipment lists. Stuff costs money. It's nice when it comes with the boat.
You're lucky. You've put yourself in a position where you really can't make a bad decision, because these are both high quality, good sailing, strong and good looking boats. Ultimately, the Sabre is a cruising boat which can be raced, and the J is a racing boat which can be cruised. Whichever you choose, you'll be very happy.