It's called "scheduled coverage" and I have it for my camera gear. It's "all risk," including mysterious disappearance. There is no deductible on my policy. In order to get the coverage, the item must fit in one of the categories defined by the insurance company, such as camera equipment, jewelry, furs, etc. With my insurer, i'm unaware of any category that would apply to an iPad.
I'm not sure what deductible means. It's not a term we have in the UK. I think it's probably our 'excess'. If that is the case, then it depends on the policy, and the choice you make at time of purchase. It's normally about £50, but in my case, it's nothing.
Deductible is the amount of a cost the insuree must pay...the insurance company pays the difference. If you have $250 deductible, and the replacement iPad costs $500, then you pay $250 and the insurance company pays $250. If you want a lower deductible, you must pay a higher premium...etc.
Yes, what you call "deductible" in the US, we call "excess" in the UK. It's exactly the same thing.
How much you have to pay if you make a claim depends on the policy, but for relatively expensive items like an iPad, it's going to be far less than the replacement cost of the item itself.
Here in the US, the cost of automobiles and accidents have gotten so high people reduce the insurance cost by increasing the deductible. Of course you still have to be able to afford the deductible if needed.
Same applies to home owners, etc. Some opt for umbrella coverage, a big policy that covers home, car, etc. Some opt for a policy that covers liability over a certain amount. Big business, insurance.