We decided to have a celebration at Heirloom one night not knowing that it is a 12 course menu. Now, you can order 3, 5, 7 courses instead, but we adventurous and went for the whole 12 and split a pairing. The food was delicious! Everything was flavorful and the plates were art. I am glad we had the FULL experience. But I wouldn't recommend doing all 12 courses and a half pairing, as I was too stuffed and tipsy by course 10. I probably would have been fine at 5 or 7 courses. The hard part then will be picking which courses you want to eliminate. But that is a good problem to have.
A really cool thing is if you have a dietary restriction, when you call for reservations a week or more ahead, they can tailor their menu around you and your party.
Always call ahead as they have private parties a lot. This really isn't a drop in kind of place.