The way I see it
pros:
save 4-5k - Unlikely, more that you'll be able to find a car more readily. - Since White means he has to buy a newer car because White wasn't an option on older cars (as he explained), he can get an older car (and be in budget)
get the car in exactly the spec I want - It isn't? More choice of cars = more chance of getting the right spec - this is the second hand market, and as he did say, white is very rare.
wrapping protects paintwork - So does wax - and it looks better. Hasn't someone already posted that from their experience it's a good finish, and you can wax that as well..
cons:
does it look like real paint?
Mismatch colours in unwrapped areas (boot etc) Boot, door jams, possibly wing mirrors too. Have you see what they can do? did you see the GT-R that was linked to? doesn't seem an issue at all.
not oem
affect resale? Not if underlying paint damage is undisturbed, but you will lose the wrap cost. Except it doesn't damage the underlying paint, it's been around for years on many vehicles, It does seem to be a true claim.