I think it depends on the conditions where you live. In Nevada, we can go over 100 for a month at a time, with swings over 110. (But it's a
dry heat

)
I had double cooling units installed in mine, and would do it again in a heartbeat. I keep the house at 78 in the summer. The cabinet stays at 70.
And, if I go on vacation and shut down the AC in the house, I don't have to worry about the cabinet. Also, to say it's heavily insulated is an understatement. Believe me, the unit is heavy.
For me, it was well worth it. Bob did a great job, and I have complete peace of mind.