Just to add to why you would or would not want to use the passphrase vs. the abbreviation - I've personally found that I find it much easier to actually type a password that consists of words, names or "nonsense words" generated by Markov chains (though not usually ones generated by letter frequencies).

I am often comfortable entering in a given password on a device on which I am not comfortable unlocking my password database (or entering my password database password + keyfile), but I usually have a device which does have my password database on it (phone, laptop, etc), so my application is "it doesn't have to be memorable, it just has to be something I'll enter without making a typo". For whatever reason, I find that entering in "tidlotexidaifol" would be harder for me to do accurately than "tidy lot existence daily following" or "tidylotexistencedailyfollowing".

That said, I like this approach, because some sites (like Bank of America, shockingly), restrict total password length, making a "very long password with relatively low entropy per character" approach infeasible.