I've always thought Neil Diamond is undeniably a rock n' roller at heart.
Absolutely. His melodies and lyrics rocked well, when you listen past the production. Urge Overkill did a rockin' version of Girl You'll Be A Woman Soon, and Andy & The Rattlesnakes (L.A. band who's still together) recorded an edgy cover of Solitary Man in 1980, and it was great. Granted there aren't a lot of commercial Diamond covers, but most of his songs would translate well. UB40's Red Red Wine reggae cover is also worth mentioning.
But a number of his own recordings were quite heavy, given that he's best-known for the early folk/rock (Cherry Cherry, etc) and soon after was having hits with Play Me, Song Sung Blue and other more
mature sounding tracks. There was no shortage of heavy drumming by Dennis St John, and rockin guitars from my brother, who recorded and toured with Neil from 1971-87. Those just didn't get much radio play, while You Don't Bring Me Flowers was topping the charts. Here's some trivia about that one: both Neil and Barbra Streisand had their own recording of the song before they did the duet. So, 3 versions by 2 artists.
Bermuda