That's only 4 tokens and you should assume at least some of the combinations are already in rainbow tables. I don't know how long it would take to create a rainbow table for the whole space, which is this big:
72940^4 = 2.8304992 × 10^19
To put it in perspective, a 14-character password using only lower case English alphabet letters as individual tokens already beats this:
Then again, a random string of 14-characters is nearly impossible to remember.
The key takeaway here is that every word adds another 16.15 bits (assuming good random source and no non-random decisions by the user), whereas another character adds only 4.7 bits. I'd argue that the effort to remember another 4 random characters (to reach those 16 bits) is far more than the one to remember another random word. We're quite good with words, you know :)
