I would have to agree with the bag comments, I think it works as advertised. I have the bag and the 45 (from EE) and the whole unit is quite possibly the best "gear" we've ever purchased. My wife absolutely loves the thing and wants a 35 to keep in her car.
The 45 usually resides in the truck (always on around the "1" setting). When not in the truck, it stays up at the shed where we have no running water but we do have electricity. We're 20-30 minutes from the closest grocery store, so we've been known to throw it in the back of the Protege and make a town run. Allows my wife to make the grocery stop first, then on to the other errands without having to worry about the cold items.
Loaded full, on the "REF" setting in summertime temps around here, it will sit in the truck for 3 days without draining the Yellow Top all the way down.
On extended trips, we usually rachet strap the 45 with two 1650s in the back (D2), perfect fit. On the 88", I can get the 45 in against the second bulkhead and then squeeze 3 more 1650s in the back.
IMO, you just can't go wrong with the 45.