I always felt Roger Davis had a distinctive voice - and apparently voice-over work kept him employed beyond his DS years (time share hawking aside - chuckle). I'm also partial to the beautiful-yet-unpretentious Jaclyn Smith, who was once married to Roger, so if she saw something in the guy (enough to say "I do"), he had more than meets the eye.
And ultimately, his role as Dirk Wilkins in the 1897 storyline gave him some meat to chew, considering his Jeff Clark, Peter Bradford, and Ned Stuart characters were innocuous and bland at best.
I met Roger at one of the west coast DS conventions (where I also had the pleasure of meeting our beloved Midnite), and knowing he was friends with Don Briscoe, I cornered him for a scoop. Don was still alive at the time, and Roger Davis had spoken to Don recently. Davis regarded me not as a crazed Briscoe groupie, but as someone who was genuinely interested in the whereabouts and welfare of his friend (Roger and Don had met in college), and his rapport was friendly and earnest. For that, he has my respect.
In a book I read, Lara Parker remarked how Alexandra Moltke hated doing scenes with Roger (Davis, not Collins), but given she was so sedate, and he played everything so frantic, the chemistry was off - still, they were constantly paired up. His best scenes seemed to be with Frid, Lara Parker, and Grayson Hall - their theatrical intensities kept him grounded and his hair in place.