potato+slink

[Khalid EZZARAOUI <ezak@cybercable.fr>]

I read before that potato is a duplication of slink, and the potato's
tree are just link to slink.

And each time a new application is generated to potato the link to this
become a new file.

So if this is true, why using slink+potato but not just potato in
apt-source?
        in fact i understood that if someone is using slink + some
potatos it is usefull
        but with apt that make an auto upgrade it is really dangerous.

I ask this because i want to have a new computer with slink+some_potatos