Comfort is a matter of opinion, not fact. My son preferred the umbrella stroller over the bigger stroller, your kids may not.

As for storage and sun protection, well, you shouldn't be counting any stroller to serve as adequate sun block - the angle of sun shifts all day long, you know, and so does the angle of the stroller toward the sun. Protective clothing, including a hat, and sunblock are what parents should be using as sun protection. The mesh bag for the back of the stroller cost me $3, and slide off easily so I could tuck it into the carry-on - that saved loading and unloading the stroller many times every trip.