I built a Night Heron Double. From my perspective it is a better kayak than the Guillemot Double. It is 21 feet long,so is a bit more difficult to manage off the water.

Tandems usually have a lot more stability than singles. In fact I would be prepared to give up a lot of the NH double's stability to get a more compact kayak.

Doubles often have a lot more volume. Because my wife is about 5 ft, she is a bit swamped by the NH double and finds it easier to paddle if her seat is raised quite a bit.

We paddled it a bit before I built her a single. Recently I had two situations where another paddler benefited from the fact that I was paddling the double.

On the first occasion, I was with a group and paddling with a male friend who was fairly new to paddling. A woman in a single was really struggling to keep up with the group, so halfway back on the return trip, I moved my paddling partner into the single and the woman into the front of the double. She had fallen well behind the main group, which included her husband.

In no time at all, we had caught up to the group and I could tell that she felt very satisfied with herself as she cruised past her husband and left him behind as we continued on.

On the second occasion, I was paddling with my son in the double and the wind had picked up quite a bit. A woman in the group in a single was so nervous about the choppy water, that she had resorted to walking her kayak around the edge of the lake on the other side. My son and I paddled back across the lake. I paddled the woman's single and my son moved to the back of the double. The woman felt much more comfortable in the front of the double in spite of the occasional wave just splashing a small amount of water into the cockpit.

Your wife may be a confident paddler, so the benefit that a double has of giving confidence and experience to an otherwise nervous paddler might not apply.

In my local paddling group there is one couple that always paddle a double and another that sometimes paddle a double.

Once my wife had her own single, she much preferred that to the double. I suspect the only way to really be sure of whether you would be better off with a double is to spend some time in both singles and a double.

They work for some people. They have advantages, but also have disadvantages.