Andy
In the view of many, myself included, the concept of a Class D tower controller having a much reduced area of responsibility making it safer doesn't hold water.
Imagin the poor sod having several IFR, which through ATC co-ordination, the Tower will know about, roll up on frequency at 15nm, along with several VFR popups.
Practice in the immediate past was to contact Alice Tower, for example, at 60DME. They would then issue onward instructions, occasionally imposing speed control. The Tower had a complete picture of what was coming and enough distance to massage competing requirements and priorities. Soon (Alice tower looks after Class E to FL125 until about Jan) he'll have only a few minutes.