I use the cheapest multi-purpose compost I can buy - usually about a fiver for a great fat 145 litre bag from B&Q or Homebase - and I always (underlined!) sieve it.

I then use the "nuts" from the sieving as a drainage layer in the bottom of the pot, and as an anti-pan mulch on the top. It works out well!

For seedlings I use the compost as sieved, and for potting on I add a small sprinkle of slow-release fertiliser granules, on the grounds that I think seeds germinate/grow better in a fairly poor "soil". Oh, and for seedlings I omit the top mulch layer, assuming that it might be too much work for their little heads to push the "nuts" aside.

And yes, the compost is peat-based: I have tried non-peat based and find them to be very poor, both in nutrient content (as evidenced by plant growth) and in structure, being very hard to "wet" adequately.

I don't add any water retention granules or anything fancy.

I find I get the most reliable results using those propogaters with water in the bottom and capillary matting: they seem to work just as well outdoors as indoors, and if you forget the watering for a few days, it's not a disaster!

Hope this helps.

PS Sacha, what's ZooPoo?