> Paolo makes a good point too.
> The optimized == nil trick is a Character or Byte Stream thing anyway.
> - this let files, Files are long
> - but ReadStream can be used in short String processing too
> There I must inquire for performance drop!

You should also make a list of places where next == nil is used.  Are 
there so many really?  Can they do something like

p := self position.
size := (stream setToEnd; position) - p.
self position: p.
size timesRepeat: [ ... ]

It might be faster or slower than next == nil, who knows...

Paolo