We sought out a 5 x 5 Boggle set expecting to be able to find more and longer words, but paradoxically because of having six cubes with vowels on all six sides, and not mixed up with the consonants, we now paradoxically get less, often we get four 'E's adjacent to each other. In fact too often we cant even find one four letter word, whereas with the 4 x 4 sets this hardly ever happened.
This must be why we see sets of 25 Boggle cubes for sale on their own on Ebay, the manufacturers obviously had to supply a more viaable distribution of all the letters.