You confuse me.
In my book if something is constant, that the associated rate is zero. Per definition...
The devil is in the definition. I think you need to re-think your space-frames here. "constant pitch and roll attitude"
in relation to the earth requires a constant input of attitude change in one or more axes
in relation to space. Hence the 'IRS conundrum'
So - how does a 340 manage to fly, anyway?