I have noticed that Americans have (broadly speaking) two ways of pronouncing the long "ee" vowel as in "fleece".
A simple [i] that ends with the same quality it starts with: listen to user MinimalPairsChicago from Chicago
A glide, (diphthong?) that starts from a position similar to the vowel in "bit": /ɪ/ and ends in /j/: listen to user falconfling from Texas
I have found that people who pronounce the glided version (ɪj), also pronounce the simple vowel in other places: listen to falconfling say [tɹikəɫɪj]
Also, the glided version occurs more often at the end of words, e.g.: "Danny", "really", but I haven't been able to hear it when it is fortis-clipped (before voiceless consonants like k,p,t and others). Also, when shouting, people usually glide the vowel.
My question is: How do Americans perceive this difference? Is one pronunciation more dramatic/educated/melodic than the other? Which accents tend to use which type of sound? Is there a more structured way of saying which sound is used depending on the environment (e.g. according to adjacent sounds)? Is there any research done on this?