JK,
The answer must be, can or can't you machine it yourself?
There are lots of plans on the net for QCTP's, but they are usually someone's idea of their ideal. Which usually means, when you run out of holders, you've got to make a load more specials.
Whereas if you go for a commercial unit, like a piston or Dickson type, the tool holders come ready to drop on at a very reasonable price. The piston type being the cheaper of the two.
The main advantage for the piston type is that if really needed, just one special cutting tool, a 60deg dovetail, and you can easily make whatever obscure holder you want to.
Everything has to be personal choice in such matters.
What works for one might not work for another.
I have used both Dickson and piston types on all my lathes, both have good and bad points, but IMHO the piston has the edge, purely because of what I mentioned above about making your own holders.
But that is just for me, you will have to make your own choice.
Bogs