I have both and like both for different purposes. For coping crown and other trim molding etc. the Collins is great. It does take some time to get comfortable with it but it's very quick and does an excellent job. If you get the Collins coping foot, make the crown jig, it will make life easier.
I like to use the RAS for scribing cabinet sides to the wall particularly when I am taking off small amounts of material on long runs. I found the RAS effective but not as accurate when using it to cope tight curves of a crown molding.
Tim