They have 750hp engines, so would have no problems with gradients. They would, however, be hopelessly uneconomic on fuel usage on a rural route and would demand a far higher track access charge due to their heavier axle loadings.
With five carriage trains where would be no possibility of pairs of units running as far as Crianlarich to serve both Oban and Fort William, either: As mentioned above, an important facet of West Highland line operation for the past twenty five years.
Similar limitations (fuel usage, axle weight, track access costs, joining/splitting) would also face five or six carriage loco hauled formations, with the added need to keep an additional loco at Crianlarich to take one portion forward.
I wouldn't say no to a buffet on a three carriage unit, as per the former Hull Trains 170s, though.