Hi Mickey
i have just bought one from ebay.. unfortunately winter has just arrived (lots of rain) and im busy at work so i havent had chance to play.
i have the DF version with the focus clutch built into it (the focus ring moved back and forwards to engage it)
impressions are..
its HUGE! its a 72mm filter ring, weighs in a fair bit too (not sure on weight)
it looks a little soft at 2.8 from the few hand held test shots i have done but from about f4 it looks very sharp. balances quite nicely on the k20 tho
focus seems good in low light and pretty quick (im from a recent p&s so im finding the k20 rapid anyway!)
seems very very well built
what else can i say?

the price you mentioned is a bit below what i paid.. but Aus is generally quite pricey for used pentax!
Thanks
Steve