We had a black cover and when it de-laminated we switched to a clear cover.
Your questions with my answers:
1. Lifespan of bubbles: we didn't even get two full seasons out of the black cover - by July, we were getting black dots in the pool from de-lamination. We are on our fourth season with the clear cover and it's just starting to delaminate. The black cover got extremely hot once it was rolled up out of the pool and it definitely needed a cover put over it to keep it away from the sun's rays.
2. Heat: during the day the black cover would heat the top of the water to a higher degree than the clear one did. However, the bottom of the pool remained cold. By the time top and bottom mixed, the extra heat on top was canceled out by the extra cold water at the bottom. Actually, I had done a bucket test several years ago where I set three clean cat litter pails filled with water the same temp into the ground and covered one with some bubble wrap, one with an extra piece of the black solar cover, and left one without a cover. The next day I mixed the water and took the temps of each, and the bubble wrap won by a couple degrees.
Since it's sun that warms the pool, we decided we wanted the clear cover that would let the most sun in (but it does decrease the sun's rays by 30% as opposed to a pool with no cover on it), so it still helps with less chlorine loss but allows the most heat to enter pool while keeping it covered). We've maintained our chlorine levels properly and haven't had a problem with algae.
3. Heat retention at night: since it's evaporation that causes heat loss, the color of the cover doesn't matter.
4. Looks: (my own question) we agree by far that the clear cover looks the best on the pool - it almost looks icy which is a neat look.
Hope this helps you to make up your mind!
Best, Jan
Jan