I think by the time that Loganair are considering replacing ERJs for their longer and wider routes, the SpaceJet M100 could be a much better choice than the E170 with their high seat costs. The M100 would certainly look great in the Loganair livery, as they look a lot like grown up Saab to me with their similar layout and proportions.
That is, of course only if Loganair could get them for a reasonable price.