Quote - I would like to use P6 but it's just too damn slow on my poor old 'puter :)

Don't be sad, it's very slow on my poor new computer too...  :-D

Primary advantage of Firefly isn't speed, nor stability, unfortunately. It's that you get a simple tool perfect for newbies, with enough advanced option to cater for the veterans.
It's easy to learn too. A year ago I was a perfect Poser newbie; A year later I don't think there is some rendering option of Poser I don't know well.