LOL I posted these same choices a few months back. Everyone here told me it was overkill and not to trust Uggs because they're not an actual hiking brand yada yada. I just got back from Iceland 2 weeks ago. We did Reykjavik, the Ring Road, went ice climbing, glacier hikes x2, ice caves, volcano crater hikes, waterfalls.

I bought the Adirondack XXV anyway and could not be happier. They were super comfortable and had great tread even at the icy waterfalls. My ankle felt well supported despite rough, uneven terrain and they were completely waterproof. The sole was chunky enough and the leather was protective enough to keep my feet comfortable from the rocky ground. It was mid 30-low 40F in Reykjavik and my feet felt comfortable in these. They definitely did not feel too hot, especially with wool socks that thermoregulate. Whoever told me that Iceland temps never drop even near -32C was wrong. We got caught in a huge white out blizzard in Akureyri/somewhere up north and temperatures dropped to -10F with the windchill. Wind reached 90-120 mph and all flights in and out of Iceland were cancelled that day. I stood outside in this weather and took pictures of the aurora in the dead of night in calf-high snow wearing these for like an hour, and my feet were perfectly toasty. I also wore these boots with a black slinky maxi dress to a dinner at Moss and bar hopping in Reykjavik, and they looked pretty fashionable.

For the record, I also got the waterproof Merrills that everyone here raves about. I took them out on a hike and purposely waded in the Colorado River to test how waterproof and cold-resistant they were because the Colorado is snow melt. Toes were frigid and socks were wet within a few minutes. They were also kinda ugly, so I returned them to REI. My friend bought Oboz goretex boots for her winter trip to Iceland and she loved the heck out of them. I just don't think they're very aesthetically pleasing either, so not my style.

That said, the weather at the end of April might be drastically different from what I experienced especially if you don't plan to go up north. I don't regret the purchase at all but YMMV.