5 gallon MLT is awfully small. If you would like to brew big beers, it might be too small for the grain bill. It's pricey, too. You can build one for half that price. There's a few threads that explain, in detail, how to build a MLT. I think mine cost ~$50 to convert a 10 gallon cooler.
"Need" is such a relative word. I'm at the point that I "need" a brewstand.