need for lined toilet tank?

I've been advised that a lined tank is not necessary with a Toto Aquia II because the full tank does not empty with each flush and large amounts of cole water are therefore not an issue. We draw our water from a well; it is very cold; and we have always had "sweaty" tanks in summer, even though they are lined. Can anyone provide experience and/or advice on this?
Thanks.

That sounds right.
Only some of the water leaves the tank.

Or, you could look at the Toto Drake with insulated tank.
The tank would be ST743SD

The complete toilet would be CST744SD