K-x shake reduction effectiveness?

One of the main reasons for my purchasing K-m and now K-x is because of in body sr to reduce costs of future lenses. I have not done any proper tests yet but have some nagging doubts that it is as effective as I had hoped. How many stops (if any) do people generally reckon they are saving and how does it compare with other Pentax DSLR and others come to that. (My previous camera, Panasonic superzoom was unbelievable wrt this)

An article from AP suggests about 2 stops advantage using SR. link

Yes - that's the theory but it varies greatly between individual cameras and IS systems. I wondered if anyone had thoughts specifically on the K-x and how it compared to others.

There's been a lot of talk about this :

link

It's said the problem could be caused by excessive mirror slap. Seems there are a lot of slappers about!

Odd, my reply didn't appear. Anyway, concerns over. Did some testing and seem to get about a 2 stop advantage and it's pretty consistent. Guess I was spoilt by the Panasonic OIS whih is mega.
Dave