I have the Impress and if I could afford it I think I would get the one made by Nortel. There a some things I don't like about the Impress but since it is all I can afford at the moment I am making do.
A deburring tool is what you need to remove the rough edge or you can also use a round file.
I use the small tubing cutter and it works fine, doesn't squeeze the end if you don't tighten it down too much.
Don't try to tighten your core all the way down with the corer. If you leave a tiny little gap and then tap it gently with a chasing hammer on the outer edge with a downward motion it should bevel nicely. At least it works for me.
Colleen