Bonnie did seem more credible, or rather, Patricia McPherson did, in the role. I've read a couple of those old interviews with Rebecca Holden, and it seems to me that if the powers that be had just let her put more of 'Rebecca' into 'April', then her character wouldn't have been so objectionable. The writers aimed
at making April into eye candy, that's what is so annoying.
But yes, Bonnie was a better technician - April suited more the 'executive assistant' role she seemed to fall into. I like to imagine, however, that April was hiding a deeper, more intelligent level, and playing dumb because that was how Devon 'Elbow Steerer' Miles and Michael saw her