How do you determine when it is time to replace your equipment? Is it a capacity decision, a financial decision or a reliability decision? Do you review all of your upgrade options or just trust that your chosen storage vendor?
Since your storage solution has to last 5 to 7 years it pays to take a long term veiw of your service , support and upgrade costs. Also remember that your storage vendor contract is negotiable, you have to ask for them to put license transferability in the license agreement and also you should make certain to put a not on you PO mentioning that you would like to have the ability to use third party support as an option in the future.