I found this thread a little too late. Last weekend I went to Lowe's to buy a Rubbermaid cooler. Sitting next to it was the 48qt Igloo Ice cube for less than half the price. I figured I was getting 2 extra gallons of space for cheaper.
The cooler did not have a drain plug built in, though it did have the groove in the bottom for a drain. I have already drilled and installed a ball valve, sprayed Stuff foam into the hollow lid, started working on my fly sparge manifold, and installed a braid in the bottom. I've just not yet used it. I guess I can look forward to some temp drops.
The I still have some gaps in the foam in the lid so I will drill a few extra holes and fill those up. I plan to give it a test run this weekend.
Price was a big factor but the size also played a pretty big role in my decision. I used a borrowed Rubbermaid when I brewed a Founders Breakfast Stout clone, which had it pretty maxed out. I'd like to make some pretty big beers this winter so a slightly larger cooler with similar footprint seemed right.