I mostly play at Pokerstars but I could find no policy on use of such software as Rubin mentions.

I checked Party and it seems to me the gist of their policy is as follows:
They check users for use of prohibited software such as Bots
and software which accummulates statistics on other players.

I agree with Rubin. Knowing the basic stats (%4th, %Raise, %SD, Win Rate, etc) would be great. But it looks to me like Party would find this in contravention of their policies.

Have you heard of anybody having their accounts closed?

In your opinion, is the use of this type of software cheating?