Years ago before I did any research on Cat Nutrition, I used to feed almost no wet food. I had one cat who died from Kidney problems and another from cancer, so I started researching. I won't go into a lot of details here, but suffice it to say that after we switched from Science Diet and Royal Canin to Blue Buffalo (Wilderness and Finicky Feast) our other kitties' skin, fur, breath, stools, and vomiting all improved dramatically. They seemed much healthier overall.
Later, I learned that more moisture in their diet not only improves their skin & fur, but it helps to prevent kidney problems (function, stones and crystals.) So, I started feeding them one meal of wet food each day (Blue Spa Select and Innova Cat & Kitten.) The improvement was dramatic once again.
Now we are taking the next step - I'm switching them to Grain Free. I just ordered Wellness cans (Turkey & Salmon, and Chicken) and Core dry. Also EVO Cat & Kitten. Additionally, I'll continue giving them a little Buffalo Wilderness to snack on occasionally.
Oh, Blue Buffalo has some very good basic info about Dry foods on their site, along with a comparison tool. The tool only compares against common brands rather than other high quality brands like Innova and Wellness, but it is still very informative.
Bottom line IMO, I would definitely not let them eat Science Diet,
and I'd give them at least one meal of wet food each day.
Your kitties will thank you!